What is a ridge

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Ridges- What are they?

The ridge is the apex of roof. This is the upper part where the two pitches meet at the top. Ridges are designed to close off the top of the roof and prevent water getting in and the wind lifting the upper rows of tiling. Roofs tend to get ignored if they are working. But when they fail a rapid response is required. So why not get to know yours.

Wet ridge

Traditionally these have been held in place with sand and cement or mortar. Depending on the quality of the mix used lasts between 20-25 years. Although we recently found one that had lasted some 45 years. The quality and life expectancy does seem to have dropped in recent years due to workmanship. The NHBC supports this with well over half of all claims on its warrantees coming from failure of mortar used on roofing. The first signs of failure often form with small sections becoming detached and cracks forming between the tile and the mortar. Often this can be hidden by moss growth. The other sign of failure is when standing far away daylight can be seen between the vertical gaps between the tiles. This is normally the sand and cement washing away due to a weak mix.

Storms and insurance

During Storms such as the recent Storm Arwen, the main areas of damage are normally the ridges. This is due to the failure of the sand and cement holding it in place. Many insurers will decline this as “storm” damage as the storm has uncovered a weakness in the sand and cement rather than being the cause of the weakness. Hence wear and tear. This is supported by many case studies from the financial ombudsman service. These case studies are interesting reading and if you are thinking of making an insurance claim for storm you would be well advised to read some on this link. Before making a claim.

Dry Ridge

Driven by the insurance industry there have been changes to the British Standard for pitched roofing. One interesting change involves the ridge tiles. The newer standard bought into force on March 1st 2015. This states that sand and cement alone is not sufficient to hold ridge tiles in place. They refer to mechanically fixed systems. These dry systems limit the need for repointing the roof every 20-25 years. They hold the tile in a plastic clip screwed into place. Below these are a comb type detail designed to help ventilate the roof as well.

Verges

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Verge
Wet verge

What are roof verges?

In the surveying context, a verge is where the roof meets the gable or flank wall (or detached side of a house). It is the weather-proof junction between walls and roof. While surveying with the pole camera we get a good view of these! Sometimes they can be seen well from ground level if there are no houses in the way. On Youtube, we have uploaded a brief video outlining the various types of verges and you can find it here:  

Wet verge

This detail or component was normally finished in sand & cement. Exposed sand & cement details tend to have a life span of around 25 years before they start to crack and detach; in some newer builds, this seems to have been reduced to 15-20 years as a result of poor mixes. The underside of this detail is called an under-cloak. This was often made from boarding containing asbestos; otherwise sheeting or plain tiles were used. A timber “ladder” was built under this and these often slip or have rot issues. This problem normally manifests itself as a slight gap between the end tiles and the tiles right on the edge of the roof.

On later works, metal clips are embedded in the sand & cement; these overlap onto the tiles, clipping them in place The sand & cement literally does get wet, absorbing rainwater. It often encases the ends of the timber battens, which can cause these to rot. If the depth of the sand & cement covering is thin, the timber may become exposed which speeds up the decay process. Sometimes they are subsequently hidden beneath profiled UPVC boards as a quick fix.

Dry verge

A more recent innovation is the Dry Verge. Dry verges attempt to improve on the reduced lifespan of exposed sand & cement and come in two different common types.

We often see the cheaper and quicker-to-install type of dry verge, the “omni-verge”. This consists of a profiled, moulded piece of plastic which follows the line of the roof, to enclose the tile and wall junction. These can perform satisfactorily as long as they are well fixed. However, they are more vulnerable to wind damage and detachment than the wet verge. Visually they are not particularly attractive because they appear to be a cheaper option.

The Rolls Royce of modern verges is the cloaked verge. This uses pre-formed tiles cast at 90⁰ that match the profile of the tiles on the main roof. It encloses the junction well and does away with the problems of exposed sand & cement. These tiles are interlocked into the roof covering so are naturally a much better fix. There should be small plastic clips between each tile; often these fall out or are omitted and if that is the case, they should be replaced. And these pre-formed tiles give a great aesthetic finish to the roof!

Pole camera

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Pole Camera
4 storey to check on the roof

How did it start

Since our first video on you tube in 2013 where we used a large aluminium pole to get up to 12m in height. This was hard wired from a camera with a long USB cable. The technology was in its infancy. We were early adopters. The pole was very unwieldy and only used on the larger taller properties we surveyed. So, we had a smaller 8m pole in regular use. We have used a pole camera on every survey since. However, the pole length grew to 10m fibre glass which was fine for 2 and 3 storey properties. We used a high-quality camera linked by wifi to pad on the ground controlled by the operator. The pole camera gives a unique view of some elements of roofs that you would not be able to see from the ground. We first did pilot schemes with insurance companies to use them in storm claims in around 2010. They are much slicker now.

How do surveyors look at roofs?

Traditionally it was through binoculars. These are still useful for close up examination of flashings and chimneys. They have fallen out of favour due to the high-powered nature of modern digital cameras.

Other surveying practices have started using pole cameras in the last couple of years intermittently. However, the pole lengths are often shorter 6-8m and will not get above chimneys for example. The camera quality is often basic web cams which give blocky images. The low-resolution images cannot be effectively zoomed in on for a better view of a defect.

The skill is not just taking the picture. The analysis of the defect is all important. Without skill and experience looking at these images’ things can easily be missed. The surveyor must have time to review the images carefully after the survey.

What’s next?

We have been looking for a more effective camera pole ever since to keep a competitive edge. This resulted in us using Carbon Fibre. This is strong and very lightweight and still remains stiff in even in high winds. The largest pole we currently use is some 55ft long. Although it has not used to the full height as this will easily do a four-storey property and chimney. Four stories are the limit of our insurance anyway.

Whenever we are seen with the pole cameras. The question of drones always arises. These cameras are better in wind and can get closer to the important eaves details as we discussed in this older blog.

If you are looking for a survey and the surveyors say they use these cameras. Check they are high resolution images and what height they can effectively go to.

Breathable felts

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Breathable felts

The history of breathable felts.

Breathable felts were first thought about in the 1980’s. They started in Germany as a result of changes in their building standards. The first patents were made in 1983. However, such felts were not widespread in re-roofing in the UK until around late 1990’s. They began replacing the plastic grey Monarfoil felts which caused significant condensation in roof voids (Sarking felt or underfelting through time – Part 3). So, if you see a white, blue or green felt in the loft you know it is a modern felt and less than 25 years old. It may not necessarily be a breathable felt, but it can help to give an indication of the age the roof.

Although breathable felts are the optimal product to use today, some modern felts are not breathable. These rely solely on lots of other ventilation details being present. This will help the roof to breathe and reduce the effects of condensation in the timber components of the roof.

What are breathable felts?

Breathable felts are very clever when correctly laid. They are very strong made from non-woven polypropylene. They are resistant to UV degradation. Although if left exposed to the elements will eventually shred or rip. This is why eaves carriers became best practice. Changes to the British Standard 5534 in February 2015 included these plastic trays that hold the bottom of the felt up where it meets the gutter.

The problems with modern felts.

The makers are very specific about what other details are needed. Although these differ between manufacturers. These may include ventilated ridges, or hips. Where an air gap is left at the top of the roof to allow for better air flow. Vented soffits where the soffits have grills to increase air flow. These are often omitted in the mistaken belief that breathable felt on its own is sufficient. We have made a YouTube video of what happens if these details are omitted. https://youtu.be/GNsB8qc-_ns

The risk of overstretching felts is another challenge for roofers. The felt should drape over the rafters and have some sag. Clearly a roofer doesn’t measure the sag on each piece of felt. It would take forever to install a roof, but 15-25mm is generally acceptable. Remember that the purpose of roofing felt is to divert back into the gutters any rain that is driven beneath the tiles by the wind. The correct sag allows that wind-driven rain beneath the tiles to run down the felt without touching the wooden battens and causing them to rot. You should be able to get your hand between the felt laps; if you can’t, it is too tight. There are visual signs of this defect; mould growth to newer felts is a symptom of over-stretching. Once stretched this will shorten the lifespan of the roofing battens and the roof will require re-felting again.

Sarking felt or underfelting through time – Part 3

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Modern Monarflex felt
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Sarking felt or underfelting through time – Part 3

The next development was in the late 1980s/ early 1990s when builders used a reinforced plastic felt called Monarflex Monofoil. Originally designed for commercial applications, its inherent strength saw it find its way onto residential developments and re-roofing projects. It is in essence a reinforced plastic type sheet. It is usually apparent as a light grey in colour in the roof void.

The composition of this layer remedied the problems of decaying found in older felts. It should have been popular for a great deal longer, however it did not deal with the ventilation issues. This didn’t allow the roof structure to breathe. It was also laid fairly taut, being stretched across the rafters, and this further limited air flow through the roof voids.

Related condensation issues

As this felt was non breathable, it suffered terribly from condensation related issues too. Water droplets formed on the underside and ran down to soak the timber elements of the roof structure. It was supposed to have a vapour layer (another polythene type sheet) installed at ceiling height. This would have reduced the moisture travelling upwards into the loft but it was rarely installed. The legacy of this underfelt in domestic housing was condensation !

Recently we inspected a property where Monarflex was present and a loft conversion had been carried out. The insulation below was wet to touch due to condensation forming in the hidden void.

Dealing with condensation in the loft void

Some actions can help reduce condensation levels in the loft void. The damp air may be removed at source with extractor fans.  The often-missing vapour layer at ceiling height may be installed. This would require caution around services such as downlighters, wiring and ducting. Holes would have to be inserted for these and the loft insulation would need to be removed and refitted/replaced. External provision such as vented soffits and ridge and hip detailing could be made. But if you are going to this length, then simply re-felting with a more suitable underfelt may be a better option.

Sarking Felt (Part 2)

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Lapped Sarking felt – Part 2

Bitumen Felt
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As building material supplies became more scarce during the housing booms in the 1930’s we saw the growth of the “half-lapped” tile instead of double lapped roof coverings. These tiles appear more stepped. The tiles are not actually half lapped, but only lapped by around 7-10cm or so. Roofs were often quite steeply pitched at that time. The need for underfelt became acute, as wind-driven rain could more easily get between the tiles and into the loft space.

Layers of sarking felt consisting of basic hessian soaked in bitumen were used. The bitumen itself is not UV stable and the hessian rots when wet. This was commonly used for nearly sixty years and is still present in many of the roofs we inspect nowadays. It is evident in older properties: we have all looked up into a loft space and seen the black material draped over the rafters.

What problems does this cause?

Around the eaves, any wind-driven rain that penetrates between the tiles should run down the felt and back into the gutters. The most common failures are when the sarking felt detail along the eves has decayed and rotted away; the rainwater is likely to get into the tops of walls.

The felt does become brittle with age so under wind loadings it tends to rip and tear and fall away, exposing the underside of the tiles. It can aggravate condensation-related issues in roof voids as it is not breathable; this often results in wood boring insect and rot.

There are suggestions that this type of felt requires complete replacement every 25 years or so. We hold the view that often the exposed areas of felt can be replaced around the perimeter of the roof. The presence of bitumen sarking felt does give a good indication of the age of the roof hence its life expectancy. Older Bitumen based sarking felts also sometimes contained Asbestos.

More recent materials

In the 1950’s due to building material shortages, a felt called “SiselKraft” was used. This comprised thick gauge building paper, laminated with a bitumen core. This really only had a maximum life span of 25 years because it simply shredded under wind loading, it is seldom seen now except for the odd piece left in a roof void. It was used extensively on Precast Reinforced Concrete “Cornish” properties and in social housing but has literally fallen away now. 

The trend for roofs with a shallower pitch became common in the 1960’s and 1970’s, with the continued use of concrete tiles. This is when we started to rely on stronger underfelt for protection and not just as a secondary “emergency” layer to keep out dust and leaves. It was still a bitumen base reinforced with string like fibres.  Even a basic rip or tear can allow water penetrating beneath the tiles to get into the ceilings below. Especially in areas with high wind exposure such as on hill sides and anywhere with a good view!

The concrete interlocking tiles usually appear sound from the outside but the stains on the ceilings below will suggest that the felt is past its prime.  Hence even in properties from the 1970’s, we often recommend re-felting with a stronger modern breathable felt.

Sarking Felt (Part1)

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Shows a roof with no Sarking felt
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Sarking felt or underfelting through time

Keeping the rain and wind out of your attic depends on the pitch of the roof, type of felt, the types of tiles and how those are laid.

When slate was used for roof-coverings in Bristol, these were generally quite thin and they were laid with substantial overlapping. Hence a layer of underfelting was not required – the rain and wind couldn’t penetrate easily.  There were still gaps and some of the earlier roofs were “torched”;  this is where a lime mortar was applied under the tiles. Other than in very old buildings, this is seldom seen now as these roofs have mostly been replaced especially in residential setting.

In some very high quality roofs in Clifton and Southville,  timber sarking boards were used as underlay to slates or tiles;  close fitting timbers were laid beneath the tiles as a secondary layer. This was a very expensive and heavy way of roofing. We do occasionally still see sarking boards and these are quite common in the North where worse weather conditions prevail.

Over the next series of blogs, let’s look at what we do still see regularly.

Around Bristol, there is plenty of clay and this was extracted to produce small rectangular roof tiles. These are sometimes called rosemary, Broseley, biscuit or common tiles. They have been in production, originally hand-made, for around 150 years.

These were very popular around the 1930’s during the housing boom. They were double lapped so formed a tight-fitting seal against the weather. Even if a tile broke or slipped, there was another layer of tiling beneath to keep the water out. Hence an additional layer of underfelt was not usually considered necessary.

If asked about defects with felt, a lot of roofers and older surveyors often respond “They didn’t have felt in the 1930’s houses, so it is not essential!”. What should be remembered is the tile type and that it was fitted as double lapped forming a much better defence against the weather.

How long do these roof coverings last?

Some of these roofs are still serviceable having stood the test of time. The underside of the tiles can be seen from the roof voids and so can the supporting timber battens. Sometimes these break or rot over time but as they are visible, they are fairly easy to inspect.

The photo shows a roof-covering from the 1930’s that is still serviceable some eighty years later. The keen-eyed will spot the insulation pushed into the eaves;  this is not ideal for ventilation purposes although there is much better air flow through this type of roof without felt.

Older texts do suggest that these roofs will have a 90-year life span. Although this one is still in acceptable condition, a surveyor will say it is reaching the end of its useful life simply due to its age. This is when a thorough inspection of the structure is essential. The supporting timbers should be checked for wood boring insect and rot as well as for the nails rusting and general decay.

Easton

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Typical street view in Easton BS5
Typical Easton street

Are you looking at Victorian/Edwardian properties in Easton?

We have spent years surveying properties in Easton and the surrounding BS5 postcodes.  Mostly good-sized Victorian or early Edwardian houses, sadly, many suffer from what Martin in the office describes as “the trinity”; roofing, dampness and movement.

There was often a lack of maintenance in this type of property in this area over the years. Some houses have been long term rentals and suffered from chronic underfunding, then were sold off when property prices increased. Sometimes the issues were fairly major and hence were neglected; the maintenance of important parts of the building were ignored. Estate agents used to refer to the customary slanting floors and skewed doors as “Easton Creep”;  in reality this is movement in the building’s structure.

Two decades ago

Around 2000, the area was described as “deprived”; as a result, funding from the EU and Councils poured into the area in the form of grant funding. This was taken up by most home owners as the portion for them to contribute was very small.

This work often included rebuilding chimney stacks, re-roofing and (importantly) replacing undersized roof structures during this re-roofing, rendering the external walls and under-pinning them as required (a lot did) and re-building boundary walls, for example.

The last ten years

In the last 10 years or so this area has seen a massive increase in house prices, with bigger up-swings than in many areas in London. Some of this increase in prices has happened because they have been bought by a diverse selection of people bring new money into the area. Often newcomers quip that it reminds them of London in cultural and structural appearance.

So if you are looking for properties in this area, it is a good idea to seek out one that has had a great deal of the remediation work already carried out, with much of “the trinity” already repaired. You should then find that many of the expensive basic fundamentals of the house have already been sorted out.

From the road, look for matching chimneys that appear in good condition and which have been rebuilt in the last twenty years; this may indicate that the area may well have had grant funding. The biggest clue is the front boundary walls; these again appear more recent and often match along the length of the road, with only one or two being different where the householder did not take up the grant funding.

Besides matching boundary walls and chimneys, most of these houses have concrete roof tiles of a similar colour. Some examples of streets where grant funding was offered are Battersea Road, Stanley Park and Bloy Street.  Maybe have a look at these on Google Earth Streetview, so that you are aware what the rebuilt chimneys and front boundary walls look, to aid your house hunt successfully.

RICS Home Surveys

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Why the New Home Surveys Approach?

There have been significant changes in the property market in recent years. Valuation practices by lenders are changing and often no surveyor will visit the property on behalf of a lender where suitable amounts are put up by the purchaser for security. As a result, the Royal Institute of Chartered Surveyors (RICS) has undertaken extensive industry and consumer consultation regarding helping purchasers to take more informed decisions.

Their research suggests that one in four people have purchased a property without having any sort of further survey being carried out – before one of the biggest investments they are ever likely to make!  Another finding was that whilst three-quarters of the people did have a survey carried out, they did not know what type of survey they had commissioned. From our experience, we would suggest that some of this confusion is because the current RICS templates for their Level 2 (“Homebuyers”) and Level 3 (“Building Survey”) offerings look very much alike; they take a similar approach to how they report, for example using traffic light systems.

Due to our high levels of personal referrals and on-line reviews, we know that this does not apply to the premium service we have offered – our Signature Building Survey. This is comparable with the RICS Level 3 report but includes roof survey and feedback, certainly far more than the Level 2 “Homebuyers”.

What we are doing to comply with the revised RICS standards?

We have attended the RICS CPD and training events which seem to focus on making sure the customer has informed choices.  

Hence in order to keep our RICS regulated status, we must now develop a wider approach, moving away from offering solely our “we will do the best we physically can” signature Full Building Survey; most of our reviews and testimonials relate to this. We will in future also be offering the RICS Level 2 and 3 surveys and our client services team will spend more time discussing with the potential client what survey is right for them.

The RICS Standards changes will take place in June 2020. We are looking to start using the RICS templates and set wording as prescribed by the new Home Survey Standard when requested by a client.  Our tried and tested methodology of our signature Full Building Survey will continue to be offered but in addition we will also offer the RICS Level 2 Homebuyers report and the RICS standard Level 3 Building Survey. The client will be able to decide what survey is right for their circumstances. In the past, we have simply declined to undertake the Level 2 reports and sent our enquirers to other surveyors offering this service; however we are now looking to offer this to our clients during the initial telephone call or email, explaining their options.

What this will mean to our returning Clients

Our next series of Blogs will outline the differences and explain what to expect from our broadened service offering.

The demand for our Signature Full Building Surveys has often outstripped our resources over the years;  Principal Surveyor Jon Holloway and independent Surveyor Bruce Marfell are normally booked heavily in advance.

So that we can still offer acceptable lead-times with our wider provision, we have asked another Surveyor experienced in delivering these standardised reports to help provide the RICS standard surveys, as are offered by most of our competition.  These Level 2 and Level 3 templates have the RICS branding on them and are in a tabular format, not a true written report, and will adhere to the basic formats as laid down by the RICS, no more, no less. But the client will now be given the opportunity to decide for themselves which level of survey is right for them, out of our three pre-purchase options – rather than just “we only provide our Full Building Survey”!

What about that Loft Space

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  • Loft space
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Loft space

In an earlier blog, we’ve already dealt with ‘Loft Rooms’, the conversion (successful or otherwise) of the attic to habitable space. But if this is not a feature of the property you are considering purchasing, you may not be giving much though to the loft space. It seems a minor matter compared to possible structural movement, roof condition, dampness or the presence of asbestos. However, usable loft space is great for storage of those items you only use occasionally, the artificial Christmas tree and decorations, the inflatable swimming pool, the holiday suitcases…

In our reports, we comment on access and boarding in the loft space, as well as the insulation present and the condition of the rafters.  For example, “there was no loft ladder, boarding or lighting provision”. This is comment is often skim-read by the client who then files it away for later, or ignores it.

However, on Facebook recently we were asked to comment on the supply and fitting of loft boarding and a loft ladder for £810.00 –  was this a good deal?

What are the options?

  • Boarding

To supply and fit a layer of chipboard flooring, normally we would suggest around £25/m2.  This is for smaller areas, say a room where more cuts and noggins and gluing down the overlapping edges will be required. A loft space on a small house can easily be 40m2 then this adds up – say £1000.00.

  • Loft Ladders

Then you start looking at the many different types of loft ladder – metal or timber, with folding or sliding variants – and the choice starts to become bewildering.  Since loft ladders are seldom used even if they are in place, you may forget how to operate them. They can be rather dangerous! Many types drop or slide uncontrollably when you open the loft hatch and hence you risk them hitting you. Some of the locks or catches do not always engage correctly as we know to our peril. One surveyor almost lost his toe when a catch failed on the loft ladder and the guillotine action caused a rather painful few weeks of hobbling around. Cost? From £80 to over £300 for a super deluxe wooden model.

  • Hatches

Modern loft hatches have draught-proofing and in-built insulation, or may simply be a hinged timber board. We often look around the loft hatches for signs of wood boring insect . These prefer damper timber which is often caused by moisture-laden air escaping around the hatch and condensing on the surfaces. Hence some draught proofing is advisable. Some older loft hatches incorporated asbestos cement sheeting in their construction, hence incurring increased removal costs.

Weight Loading

The other issue is one of weight loading. The TRADA tables suggest that when the roof design is calculated, there are no significant weights in the loft space (the odd plastic Christmas tree aside). However, when the loft is boarded out this will increase the deadload on the ceiling joists, even before we have started to store the seldom-used artefacts. In a RICS building survey at a small house in Clifton, the ceilings were noticeably cracking. The vendor pointed this out to us, saying it was just his luck that as he put his house on the market the ceilings had started to crack. Inspection of the loft void found that in an attempt to clear the habitable areas to make the property look attractive, he had put a huge amount of contents in the loft void. This included a weights bench and set of weights. Needless to say, this had an adverse effect on the ceiling joists below and the plaster attached to them.

So simply boarding the loft can become a rather complex project. The short comment that we use to describe access and boarding in the space may suddenly have a significant cost implication well in excess of that £810.