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Pitched Roof Structures

 

Pitched Roof Structures

You’ve clambered up into the roof void, the attic. What’s the function of those wooden planks and what problems are associated too?

Unless it’s a flat roof, the upper most board that normally runs across the top is the ‘ridge board’. This is the apex or peak of the hipped roof.

Then running from this ridge board to the walls are the rafters. These are normally 3”x 2” in Victorian housing; in the 1930’s, the thickness was increased to 4”x 2”. Yes, imperial measurements, not metric, in those days!

The rafters have to span half the width of the house, so they are normally supported mid span by a large timber called a purlin. This stops them bowing or sagging under the weight of the tiles. We have seen purlins as thin as 4” x 3” in some properties in Gloucester Road and St George. With better quality Victorian housing, say in Fishponds, they can be up to 9”x 3”.

These are often supported mid span by a diagonal brace (called a strut) to take the loading (weight) to the central spine, the load-bearing wall in the middle of the property. Otherwise, the strut may be fastened onto binders. These are timbers spanning across between the load-bearing walls to stop the purlins bowing.

If you have read our blog on Pitched Roofs, you will know about ‘roof spread’. Sometimes even these reinforcing  arrangements were not enough, or have been removed, so additional struts were also used,  sometimes with collars. These struts run between the rafters just above the purlins, to give triangulation to the structure.This sends the weight loading down to the load bearing walls at 90⁰, preventing them from spreading and pushing the tops of the walls outwards.

Types of Roof Structure

Before the 1960s

Before the 1960’s, most roof structures were of traditional cut timbers, sometimes called “carpenters’ roofs”. As it sounds, each length of timber was measured and cut by hand, then lifted into place and secured with nails.

There were various designs of roof around during the Victorian era.  Inverted or Butterfly roofs were very common in Totterdown and Easton.  These have a central valley running down the middle to take rain water away so are prone to leakage. The structure is often problematic and cannot be inspected from the ground. These must be inspected from a pole camera or ladder. The valleys were supported by a ‘roof plate’ underneath. This was a substantial timber running under the valley from front to back.  These roof plates have often deformed under the weight of the tiles and water ingress issues have often caused decay. These roof styles stopped being used at the beginning of the 1900’s.Such roofs cannot easily be converted to habitable space as they have limited headroom.

In the 1930’s, usually in end of terrace houses or semi-detached properties, the sloping hip timbers run to the external walls.This hip is supported by a hip board or timber and the cut rafters around it are called jack rafters.

From the 1960s

Around the 1960s trussed roofs started to gain in popularity. They incorporated the rafters, ceiling joists and bracing into a large triangular structure. These were manufactured off site and craned into place.  Then they were fastened using gang nail plates to fix the joints together. They were quick to install and were cheaper in comparison to cut roofing as the skills required were less.

The early trussed roofs did have problems with gang nail plates rusting and failing; some properties in Horfield have exhibited this.  Such rusting is often made worse by condensation in the loft voids. The triangles sometimes tilted when installed and may not be straight and true. When some roof failures in the 1960/70’s were attributed to the domino effect of the trusses falling over, diagonal bracing became part of the Building Regulations requirements. The trusses then also had to be secured to the gable-end walls using metal straps to hold the structure together.  These are often missing in early examples of this type of roof structure and should be retro fitted.

OH, GOOD, IT ALREADY HAS A NEW ROOF…

roof

So you have diligently used our blog entries to guide you in viewing a property. You can see concrete tiles and the estate agent has said‘ Don’t worry,  it has a new roof!’ Why should you be concerned?!  Half of the ‘new roofs’ we inspect at in the Bristol area should have Building Regulations approvals and do not. Two aspects!  First, it’s difficult to sell a property without the correct approvals. Second,  the workmanship may not be acceptable if not approved.

As we know,pre 1950’s roofs in Bristol were usually covered with clay tiles (or slates) which were lighter than concrete.  Now it has a concrete roof  so we know from the planning portal that it is likely to need Building Control approvals.  This will ensure the roof structure is strong enough to support the concrete tiles. Also that Fire (Part B) and Energy Performance (Part L) criteria have also been met.

THE STRUCTURAL ISSUE

If it has been re-covered with concrete in the last say 5 years, then very little time will have elapsed. The building’s lifespan is a lot longer than ours!  And the faults linked with overloading the property’s roof structure can take years to develop. The existing timbers (the rafters and purlins) may be too thin to support the new heavier tiles. If they have been replaced, these may also be inadequate.

The replacement covering should have been constructed with input from a structural engineer. (S)He would have determined the loadings. He would then have checked that the load bearing walls were suitable for the increased loadings.

If the timbers have been replaced, they may have the stress gradings stamped on them. This shows the strength of the actual timbers.  C16 is weaker or C24 is stronger. The trada tables then give allowable spans depending on the centres.

Why does this matter? First the rafters will bow, causing the load(weight) of the roof to be sent at an angle into the walls. However, the load should besent vertically straight down to the foundations. This often leads to cracking around the tops of the walls, commonly known as roof spread.  This can be seriously expensive to repair.

Eventually the roof itself will deflect and the tiles become loose… look at the ridge line carefully!

 

WHY WOULD YOU SPEND SO MUCH MONEY AND NOT HAVE THE WORK APPROVED?

It is not normally the vendor’s fault! Roofing works are very expensive so it is likely that the cheaper quotes were accepted. From the roofing contractor’s  perspective,it does make life easier not to inform Building Control!  Awaiting Building Control inspections can delay payments and hold jobs up. And if the work is not inspected, the contractor would not be held liable for infringements at the time.

It is likely that this missing compliance “paper trail” is only identified when selling the house.It normally comes as quite a shock to the vendor!  Indemnities are often offered by the solicitor but thesemerely indemnify against enforcement action being taken by Planning or Building Control. They do not deal with the quality of the structure in any way.

HOW CAN YOU TELL?

There’s a very quick trade secret ! If the has been recently recovered and has less than 270mm of loft insulation present, then it would not comply and hence we know has most likely not been inspected. Otherwise, ask the vendor about the Building Control sign-off documentation. If that is not present, make sure your surveyor inspects the roof structure thoroughly, which won’t happen in a home-buyer’s report !

Pole Camera or Drone?

IS IT A SELFIE STICK?

Members of the public and vendors often see us with cameras on tall poles at the front of houses.  It’s strange to see a fully grown man with a giant “Selfie Stick” as lots of people call them!They are intrigued by what we are doing and ask questions.

We have been using pole or mast cameras on every Building Survey we’ve carried out since 2012.You can see us using a 6m mast in this early video.  Over the years we have continued to refine and develop the mast camera.  Now  they can be up to 15m high, as can be seen in this incarnation from 2013.

Over this time, the cameras mounted on the 10m fibreglass poles used by all our surveyors have really come a long way. They now have tilting, panning heads to allow us to look behind parapet walls and in other hidden places.They are also much lighter and easier to handle for safety.

 

WHAT ABOUT BINOCULARS?

Strangely, the uptake of this technology by surveying firms in the UK has been very limited.  We pioneered the technique in Bristol!  We are still the only firm in Bristol offering this as standard in our Building Surveys -not as an added extra at a premium cost. The others tend to look from ground level with binoculars, which isn’t going to provide a comprehensive view. You will not be able to see the tops of chimneys, second storey flat roofs or behind parapet walls. Nor into the valley or butterfly roofs that are very common in Bedminster, Clifton, Easton and Totterdown .

WHY NOT A DRONE?

The main question we are asked is why don’t you use a drone? The answer is that we don’t need to use more complicated access technology to gain a similar view.

Most importantly, we need to view the sarking felt, which should lap into the gutters on a standard roof. This felt has often decayed just beneath the roof tiles; it is very rarely visible from ground level.  From taking the pole camera out of the car and setting it up, we can see this area within a few minutes.  Setting up a drone takes time.  Imagine manoeuvring it into place to hover right next to the tiles.  Getting the camera perched in the gutter looking upwards. This manoeuvre would require significanttime and skill.  And the potential for tile or gutter damage by the drone is a possibility!

The pole camera allows us to see the tops of chimney stacks and also the tops of parapet walls. It also shows other areas of complex roofs that we want to inspect in detail.  So why complicate the process by using a battery powered vehicle that cannot be used under certain conditions?Only the very expensive models can operate when there is high wind or excessive rain or in certain geographical areas.

 

THE POLE CAN GO WHERE DRONES CANNOT

This should be seen in the wider context of drone use. The current call for registering and licensing drone pilots would add another layer of cost and complexity. This is not warranted in the surveying of residential property. We would not be able to use of them near Bristol airportor sensitive sites such as the MoD. There are also the general privacy concerns. Our cameras only look at the house we are surveying, not at the back gardens of an entire street. Hence our camerasdon’t cause alarm to people sunbathing in what they though was the privacy of their back gardens!

The real skill lies not in taking the picture, but in being able to analyse what the picture means…

 

“Loft Rooms”

Is that converted attic described as a ‘Loft Room’ in the Agent’s  particulars? Then beware – the trick is in the wording! This is often ‘agent speak’ for conversions that do not benefit from Building Regulations approvals. Hence it is not considered habitable space and as such cannot be lived in. Nor will it be valued as habitable space by the mortgage company. ‘Loft Room’ is often a snappy short-hand for major problems with the conversion!

BUILDING REGULATIONS

The Building Regulations specify the performance factors for varying building elements. Before commencing a conversion, you should submit the proposed drawings and any structural engineer’s calculations to the Local Authority, for their approval. Council Building Control Officers or their contractors would then visit the site at intervals during the course of the works. This ensures that the works are being carried out as specified in the plans. It also ensures that the correct materials (such as concrete lintels) are being used, prior to them being hidden by plaster or render, for example.

Some surveying companies offer this service commercially, so you can use their approved inspectors rather than the Local Authority for approvals. This may save you money and these organisations can offer a more flexible verification process.

Then at the end of the works and on the final inspection, a Completion Certificate is issued to the building owner or their agent.

WHY IS THE CERTIFICATION IMPORTANT?

The information and certification produced in this process is vital for later surveyors!  We do not routinely break into the fabric of the building in the course of our inspection.  If we did, the vendors would no doubt be very angry as holes in walls are not ideal when selling a property!  The Completion Certificate states that the conversion has been inspected and meets the compliance standards in force at the time of the construction.  Are you hoping to sell a property with an attic conversion but no Completion Certificate? If so, you may be disappointed at the price you finally achieve.

WHAT ACHIEVING COMPLIANCE IS LIKELY TO INVOLVE

Just taking one section of the Building Regulations as an example, Part L : the Conservation of Fuel and Power Regulations. These are designed to reduce the amount of fuel needed to heat a dwelling. Part L describes the need to hit certain “U-values”. These are performance factors of materials used in the construction of the external envelope (walls and roof). Nowadays you would be expected to have significant thicknesses of insulation in the slope of the roof for it to be signed off. Compliant materials would include Polyisocyanurate board, also referred to as PIR or ISO, a yellow type foam insulation with silver foil on both sides. The alternative would be expensive multifoil or equivalent.  Such insulation is rarely found in non-compliant older structures.

 

HOW TO MAKE THE LOFT ROOM COMPLIANT WITH PART L OF THE BUILDING REGULATIONS?

You would have to strip out all the existing internal plasterboard on the walls and ceiling in order to fit such insulation.The Regulations also normally require that insulation is left beneath the floor and again this may not be done. To check whether it is present, the floor may need to be stripped out, even partially. And the floor may need removing completely to insert such insulation to create a compliant space.

SOME OTHER CONSIDERATIONS

Other sections of the Building Regulations include Part B, bought into sharp focus in the wake of the Grenfell tower disaster. Part B Regulations cover fire safety and the need for fire resisting corridors for safe access, fire doors, smoke alarms and heat detectors. For example, does the attic conversion have fire doors? Or a robust staircase escape route?

And then there are the comprehensive Electrical Regulations to take into consideration!

SO IS THAT ‘LOFT ROOM’ AN ASSET?

In summary, if the conversion has to be stripped out to ensure just one factor is met, this will be costly. To remove the old non-compliant structure,you will have incur labour costs to dispose of the old materials, before you upgrade the conversion correctly. Compare this with purchasing a property that has no ‘loft room’at all and then converting one properly…

 

Conservatory

 

“IT’S GOT A CONSERVATORY!”

 

But that may be a mixed blessing…

It’s generally expected that a Conservatory will be a glass box attached to the back or side of a house.However, perceptions about conservatories have changed a lot over the years. For instance, a survey in 1991 by RICS (the Royal Institution of Chartered Surveyors) found that only 20% of people expected to use a conservatory all year round. By 2005, that had increased significantly to around 90%. Similarly,in 1991 only 30% of people considered it part of the ‘Living Area’. Again, this had increased significantly by 2005 where 60% thought Conservatories were part of the Living Space. This increasing use of the space makes a Conservatory more valuable and the effect of constructing one should impact positively on the value of the property.

The Regulatory Stuff

Conservatories are normally exempt from Building Regulations and Planning assuming they are constructed within certain parameters.

Building Regulations state they should be at least 50% glazed. They must be thermally separated from the main by external quality doors. They must not be connected to the central heating system but may have their own separate heating system. So if you a see a central heating radiator in a Conservatory, it normally means the construction is non-compliant.Other parts of the Regulations also apply;for example,  if you are installing electric sockets, underfloor heating connections or lights, then they must conform to Part P.

Planning approvals are not normally required if the Conservatory is at ground level and the floor area does not exceed 30m². It must also be correctly positioned in relation to existing buildings and boundaries.

What are the problems?

How old is the Conservatory? Installers may guarantee the structure or elements for 3, 5, 10 years or longer – but installers often go out of business. So unless the guarantee is backed by a separate insurance policy by the installer, it may be worthless.  And if the Conservatory is in a poor state of repair, you will have the additional cost of removing it. Older ones may be constructed with aluminium frames although most modern ones are metal-reinforced UPVC, which has a projected lifespan of around 25 years.

Some Defects

Very common defects with conservatories are the vertical cracks opening up between the Conservatory and the main building.These are most likely as a result of some movement between the more secure and settled main building and the more recent addition. This is normally combined with thermal movement. Normally these cracks are ‘slight’ and not considered particularly worrying; good use of flexible sealant can fill the gaps.

What is the roofing material? Is it expensive glass, possibly optically tinted? Often cheaper twin wall polycarbonate is used as the roofing material.  This is made of lightweight plastic sheets with extruded boxes inside the construction.  These roofs tend to have problems with condensation forming inside the internal chambers; visible water droplets appear. This is mainly an aesthetic  issue and not structurally concerning. However, when the roof sheets age, they become brittle and as a result can be easily punctured by hailstones –  we have seen them damaged by seagulls!

The metal bars between the polycarbonate sheets (often called glazing bars) have been known to deflect over time. This means rainwater and snow do not run away correctly and the water can pool;  the rubber seals between the bar and the sheet fail, allowing water to enter the Conservatory. During the heavy snow falls in 2012, we visited many properties where the weight of the snow had simply snapped the bars and caused the roofs to collapse.

Rainwater Disposal

In newer cavity walled properties,a good quality Conservatory should have a cavity tray fitted in the wall of the main house above the Conservatory. This should prevent water from ingressing from the cavity and staining the tops of the walls in the Conservatory; weepholes above the Conservatory are often the only clue to whether  this has been done. If the property is a bungalow, there is likely to be an enclosed box gutter between the bungalow and the Conservatory; has the rainwater been routed correctly away from the building?

Location

As mentioned previously, Conservatories are generally constructed at the back or side of a property which may impede access to the gutters and soffits above. This makes decorating and regular maintenance very much harder. Either protection over the Conservatory is required or very costly scaffolds are necessary. Hence in most cases it is more cost-effective to remove the roof panels of the Conservatory to allow a standard access tower to be erected.

 

 

Damp

DAMPNESS

Damp has been found in properties since we lived in caves! During the feedback sessions after our surveys,  this is one of the most worrying issues for our clients.  They often prick up their ears at the mention of dampness in a property!  A recent survey suggests that 67% of people would consider pulling out of a purchase if damp was discovered.

Why is it such a problem? Dampness does not just damage decorations, wallpapers and paintwork. Where it has been present for some time it can damage adjacent  timbers, leading to expensive structural problems. How might you detect it without the sophisticated meters that we use? During a viewing,  your best friend in this quest is your nose – damp timbers give off a recognisable musty smell. This is often hard to mask, even with air freshener or the old favourites of coffee or baking bread.

We normally split dampness into 4 categories:

Rising dampness

This is moisture rising up the walls of the building from ground level. Look out for ‘tide marks’ around the base of the walls indoors, perhaps just darker paint near floor level. Look for salts crystallising on the surface of the wall or blistering to the paintwork finishes.  Can you see rust forming on the nails holding the skirting boards or along the metal angle beads at corners? If so, this indicates that the dampness has been occurring for a long time.

Penetrating dampness

This is dampness penetrating through the roof or walls.  Look for stains around the ceilings of the upper floor, beneath the roof. Especially look around chimney breasts and under window sills for brown staining. However, penetrating damp can be easily confused with condensation as they both normally occur in vulnerable parts of the building, such as in corners of rooms or around windows.

Condensation

Condensation can occur anywhere in the property.For dampness issues beneath a room with stripped  flooring,look at the nail heads to see if they have rusted. If so, this suggests excessive moisture in the area.

Bathrooms are notorious for condensation problems so inspect them thoroughly for mould growth. This normally appears in the corners of rooms and takes on a crescent shape due to air movement in the room. Mould can also appear behind large items of furniture so take a sneaky peek behind wardrobes. This mould suggests condensation related problems. Often painted over by canny vendors, the paintwork is still darker so inspect the corners of rooms thoroughly, especially if they have sloping ceilings.

Leaks

One of the most common reasons for escape of water claims with insurance companies is failed seals.  Look out for cracks to the grouting in bathrooms and also for failed seals around kitchen sinks, baths and showers. There might even be a darker stain on the ceiling of the room below the bathroom, a real giveaway.

Also have a look underneath the WC cistern. Modern close-coupled toilets in particular often leak –and what about that plastic tub beneath to catch any drips?!

Do you already have suspicions about dampness in a property ? If you have used our services previously, just contact our office with your invoice number and we will arrange to loan you a damp meter to use during your viewing. Forewarned is forearmed, as they say –

 

Gardens

Gardens

Landscaping

An attractively landscaped garden is a great feature, but it requires maintenance, time and effort.  Is that decking going rotten? Is it dangerously slippery? Are there broken paving slabs or loose handrails to steps? Is there a pond that may be hazardous to small children?

Boundaries

First look at the size and shape of the garden; can you tell where the boundaries lie?  Does it seem regular and consistent with neighbouring gardens?  Often concrete posts are used to divide properties and demark the boundaries; see if these are visible. Is there access from a walkway or alley at the back or side of the property? How secure is the back gate?

Fences

Are the fences damaged? The cost of replacing a simple panel fence set in concrete in the ground is around £80/linear metre. Disposal of damaged material is extra. This may seem a simple DIY job but don’t overlook the cost of materials mounting up.Some sources suggest that a fence constructed to the British Standard (1722) should last around 15 years. However,careful treatment every couple of years will significantly extend the life.

You might try gently and discreetly leaning on the fence to test for movement!

Walls

Walls are constructed of many differing types of materials. They may be retaining significant amounts of soil, especially on terraced sites.  Hence,there should be holes to allow the soil to drain. Look for cracks or significant leans. Again like fences, the cost of disposing of a damaged wall is very time consuming, heavy and costly, before it is even rebuilt. We estimate £120 per square metre to simply rebuild a wall that is 9” or 220 mm in thickness, assuming that the foundations are acceptable and that does not include disposal of the old wall.

Plants

The words “Japanese Knotweed” strike fear into the heart of any home owner, let alone a purchaser. And this is becoming more common in Bristol and we are receiving more and more calls to confirm its identification. We have found it from Clifton to St George and St Pauls to Fishponds, to name a few areas. But it can be eradicated! So, if you see a plant you don’t recognise, Google images will help, but be wary of a quick identification as many plants look very similar. Some web sites do offer free identification from photographs, but often they do not respond if they are busy so don’t expect too much for free.

Trees and Hedges

Again trees can cause concerns for even the most experienced purchaser. If you are viewing in winter, remember that full summer foliage will shut out daylight. Leaf falls from nearby trees block gutters and drains. Tree roots can damage the foundations and drains, causing subsidence issues.  Such roots can lift paving, too.  Remember the rule of thumb that the height of the tree is often the spread of the roots.

is the tree a particularly large or a striking specimen,if so ask the vendor if there are any Tree Preservation Orders in place. If so, even basic maintenance will need planning permission!

And those high, thick hedges will require cutting regularly in the growing season, as well as draining all the moisture from the adjacent flower beds.

 

Floors

FLOORS

Floors aren’t just places to put soft carpets or smart tiles. They are integral to the structure of the building, providing support for the internal walls. Hence they need to be firm and reasonably level.

They are generally either ‘solid’ or of suspended timber.

Solid Floors

These are made of concrete and can be found as the ground floors of properties of any age. They may be original to the property or put in place when the house was refurbished later. They are very  common in 1950’s housing as the shortage of timber meant concrete was a cost-effective alternative.

Such floors should incorporate a damp proof membrane that should link to a damp proof course. This is an area of potential weakness! Solid floors in older properties can be problematic as often they have replaced original ‘breathing’ timber floors. So if you find solid floors in a Victorian house, look out for blistered decorative finishes near floor level, caused by dampness. Look for any movement in the floor – is it flat and level? If not, this can suggest a chemical attack or poor laying technique.

How do you tell a solid floor from a timber one?

Some properties have solid floors in parts of the ground floor (particularly extensions) with suspended timber in other rooms. And there are likely to be fitted carpets or parquet flooring, ceramic tiles or vinyl covering the floors.

The easiest way to differentiate between solid concrete and suspended timber is the “heel drop test”. Basically, stamping or jumping on the floor! Is there is any give to the floor or reverberation of the furniture in the room?  Then chances are that it is a suspended timber floor. If it is hard and your body jars, then it is likely to be a solid floor.

Is there noticeable reverberation when you impact the timber floor? If so, this may suggest issues with the joists beneath –  perhaps they are damaged or undersized. This applies to both ground floor and upper floors.

It is also very common in certain areas for timber floors to slope. The agents refer to “Easton Creep” in BS5 postcodes, as most properties there have settled over time and the floors slope. As long as the movement is not on-going, this is acceptable. Assuming you can live with it?!

Beneath the Suspended Timber Floor

Timber floors are vulnerable to any dampness as timber will decay when in a damp situation. And the ground underneath a building is damp!

Substantial decay in timber has a very distinct mushroom smell , so use your nose! What can you smell? Take a look outside – are there plenty of airbricks?  These should be present to both front and rear of the house with suspended timber floors. They allow air to circulate beneath the house to prevent condensation and rising damp building up, decaying the supporting timbers. Even when an older property (say Victorian) has been “damp proofed”, remember that the floor joists are still likely to be built into damp walls.

 

Floor boards

Frequently in older properties, floor boards show evidence of wood worm when uncovered. Are there any lighter coloured holes or small tracks on the timber? This may suggest an active infestation and may indicate that there are further infestations out of sight, possibly in the joists or rafters.  And an infestation may prove costly and disruptive to treat to prevent it spreading.  Treatment  includes lifting the floor boards and spraying the undersides of them.

Are there loose floorboards beneath the carpets? These can form a trip hazard and make a lot of noise when walked on. The soles of your feet are useful tools! Offer to take off your shoes when entering a property  – especially if the vendor is there!  This not only shows respect but will give you the opportunity to feel through the carpets for any loose boards.When these are split, cutting new boards and securing them correctly can be very time consuming.

In newer or refurbished properties, chipboard is often laid over the joists, especially on upper floors. Chipboard will sag over time anyway.  And new floors are often installed fast, meaning they are seldom are well laid with supports where the joints meet.  So these chipboard floors often creak! How much noise can you tolerate? Can you live with the creaking?

What is on top of the floors?

Do check the condition of the floor coverings, which can be costly to repair or replace.

Where high quality solid timber or engineered floor coverings have been laid on a DIY basis,  the joints can open up or sections can lift, due to poor fitting and thermal expansion. Re-laying floors of this type is expensive.

Are those ceramic or slate tiles cracked? If so, will the pattern and size be easy to match if necessary? Runs of tiles only last say 5 years so replacements may be hard to obtain.

When laminate is mopped many times, it tends to absorb water at the joints (called crowning); then it is unsightly and can be a trip hazard.

In properties built around the 1950s – 1970s, plastic type tiles were used which often contain asbestos.  Sometimes these can be identified by their deep colouring, commonly red, green or dark brown.

And do ask what carpets will be included in the sale, as well as those matching curtains…

Internal Walls

INTERNAL WALLS

Internal walls divide the living space into rooms.  They also give strength and structure to the property. Imagine putting a heavy weight on the top of a very large box – it would normally collapse. If you sub divide the box into four smaller areas and put a load on the top, it is likely to bear a lot more weight before it collapses. Houses are very similar. Large open plan spaces in buildings are often a key selling feature. Unfortunately many such open plan areas were originally sub divided, with internal walls supporting the structure above. If adequate replacement supports have been provided, fine. If not, what is most attractive can also be most costly to rectify.

SOLID WALLS

Have you seen builders tapping walls? This is for two reasons – one to see if surface plaster has blown, the other is to determine if walls are solid or stud. A dull thudding sound often suggests a solid partition. These can be made from lightweight blocks or of old timber frames loosely infilled with bricks. When viewing an older property, look for cracks which could signify movement. If the partition wall is leaning, this may suggest something has moved or bowed over time,  usually the floors above or below.

STUD WALLS

These consist of timber frames which are covered both sides with either plasterboard or lath & plaster,  depending on the age of the partition. Contrary to popular belief, stud walls can become load bearing over time – when buildings settle, weight loading can be transferred onto the timber studs. If the building is timber framed in its construction, they certainly can be load bearing! They may be designed to be structural.

ALTERNATIVE MATERIALS

After the war experimental partitions of various types were used.  Usually this occurred in system build and council houses but some types  have been revived in more modern properties. These can sometimes be identified because their thickness is less than 110mm, sometimes as thin as 50mm.

After the war, Paramount partitions were common in Bristol and in PRC (PreCast Reinforced Concrete) houses. The construction was a plasterboard sandwich with cardboard infill for strength -imagine an eggcartontype of configuration.

Stramit was another interesting one. This time, compacted straw was sandwiched between plasterboard.  These were more common in Gloucestershire. They can be very problematic if leaks happen; we have seen plants growing from internal walls as the result of a leak!

Another system we have seen in Gloucestershire, most recently in a bungalow in Coal Pit Heath, is the “clay pot” or extruded clay brick. These are similar to blocks seen on the Continent and were  mainly used in the 1930’s and 1950’s. However, you are unlikely to be able to identify these on a viewing.

DRY LINING

This is a very quick and easy way to disguise poor plaster or dampness. It is literally gluing a plaster board onto a wall or nailing it onto timber battens again attached to a wall. Where dry lining is present, normally as the inner face of external walls, be wary!  Our YouTube video shows the problem, diagnosed by using thermal imaging.  If a hollow sound is heard when you tap the inside of an external wall, be suspicious.

 

REMOVAL OF PARTITIONS

In our first section about viewing a property, we suggested looking at the floor plans of similar properties nearby.  Trawl the estate agents’ websites!  These can give you an indication of the original layout of the house you are considering. Have walls been removed? If so, they should have been inspected in advance by a competent person (a structural engineer or surveyor) to check whether they are load bearing, structural. Ask the vendor if they removed the wall or whether there is any documentation to support the removal of the wall.

If the wall was load-bearing, supports should have been put in place to carry the weight of the structure above. Sometimes smaller nub walls are left to support steel lintels or there are boxed -in downstand beams. Keep an eye out for these – if they don’t exist, you may need to insert them later. Look for any signs of stress along the line where the partition was located, or where the beam is built into the wall. Cracks or failing plaster would be probable indicators.

 

Ceilings

Ceilings

Ceilings are made from a variety of materials and each has different associated problems!

Did you read our blog on inspecting lofts and venture into the loft space (wearing a PP3 mask)? If so, you might be able to lift the insulation and see the type of ceiling material below.

Lath & plaster

Lath & plaster ceilings were used extensively pre 1940. They comprise wooden laths coated with various layers and thicknesses of plaster.  The plaster may contain ash, horse hair and lime.

While working for many leading insurance companies, we have inspected countless collapsed lath& plaster type ceilings.Lath & plaster can and will eventually fail. It happens in the most expensive houses which have decorative cornices that run into thousands of pounds to replace in a single room. It also happens in pre 1930 council houses.  Famously, the ceiling collapse at the Apollo Theatre in London in 2013 injured over 70 people. Such ceilings are seldom used now except in restoration work in listed buildings.

These ceilings are very thick,  normally around 20mm. The tell-tale signs of failure are cracking, an undulating surface and sagging. Finishes such as lining paper tend to mask such cracks but the undulations are easy to see.   Sagging suggests that the plaster has detached from the wooden laths above.  The cracking is not inregular, straight lines -it is normally diagonal and irregular.

Removing such ceilings is a very dirty job!  And it is a real challenge to save any ornate cornices running around the perimeter of the room. This dusty job is often expensive as few want to undertake this work.

Sometimes you can deal with lath & plaster ceilings by underboarding them. Underboarding is screwing a layer of plasterboard beneath the lath & plaster to support it. This is an inexpensive repair but will lower the ceiling height and you will lose any cornicing.

Hardboard

Occasionally in the 1950’s and 60’s, ceilings were constructed from thin sheets of hardboard, ie reconstituted timber. It is normally fairly easy to spot these from underneath, as they have tape over the joints of the boards. This gives the ceiling a grid like type of pattern!

Plasterboard

Since the 1940’s, ceilings have been constructed of uniform boards of gypsum known as plasterboard. These boards have a long service life.In the early days, when plasterboard was first used, the joints were not taped with a netting scrim. Hence minor thermal movements and stress cause straight line cracking, sometimes at right angles.  When this is the case, the joints can be taped  over and the ceiling skimmed. Sometimes nail pops are evident. As long as these are repaired properly (not just covered in filler) they are unlikely to re-appear.

Polystyrene tiles

These were most popular in the 1970’s. They were often used to disguise cracking or damaged ceilings. However, they are a fire hazard as they were not intumescent .  If they catch fire, they can rain molten polystyrene,  a scary image! These should be removed as soon as practicable. While removing the tiles is fairly easy, the plaster beneath will probably be damaged as a result. The spots of glue are also very hard to remove. So allow costs for the skimming often required after removal.

Timber cladding

Timber cladding was another old favourite. These are strips of tongue-and-groove wood and hence are flammable. So they can pose a risk, especially if they are used in a Kitchen. The cladding is not fixed direct to the ceiling; it is often nailed to timber battens which are screwed through the ceiling.  Removing  these will disrupting the finish beneath. Hence you should only undertake this if you are willing to plasterboard and skim the ceiling beneath.

Artex

Artex has been used since the 1970’s, an applied finish with various patterns from stipple to swirl. It was sometimes used on plasterboard instead of a skim, so the characteristic straight line cracks, often with right angles, are very common. Patching Artex satisfactorily  is very difficult and the repairs always seem to be obvious.  Hence when a section is damaged, it is often better to simply skim over the entire ceiling.  However, Artex applied prior to 2000 can sometimes contain traces of asbestos so scraping off the more pointy bits can be hazardous. If such ceilings appear damaged, then it is always best to have tested  it prior to purchase, because  removal of a medium size asbestos-containing ceiling costs around £800.00. And you will still have to replace the ceiling!