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.


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!



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.


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 !

Pitched Roofs


Pitched Roofs

Roof repairs can be very expensive, not just the materials and manpower, but will possibly require scaffolding as well. So take binoculars or a camera with a powerful zoom to enable you to visually inspect the roof covering.  You can do this at any time, without the agent having to be present. As always, look at the neighbouring roofs see if they have recently been re-covered, a good indicator of when yours will need doing.

What is the roof covering ?

Next, focus on an individual tile and try to determine what it made of, clay (older) or concrete (more recent). In some areas, older properties have real slates. Concrete tiles indicate a post-war roofing replacement. Is there anything special or unusual about the type of roof tile? Some tiles such as Triple Deltas and Bridgewater tiles are not as readily available as more common types such as Pantile or Double Roman.Hence they are more expensive to repair or replace.

Can you see any defects?

Are there any slipped or missing tiles? These indicate a lack of routine maintenance but also water ingress is very probable.  Water can cause damage in a timber loft space which can be very expensive to repair! If there is some lighter colouring of the surrounding tiles, this may indicate a more recent break or slip.

Is the roof a “patch work quilt” of differing colours of tiles? Probably someone has made many repairs and it may be time to replace the roof covering completely. Also, look out for small grey tags known in Bristol as “tingles”; these metal (usually lead) clips are used to secure individual tiles and they indicate localised repairs have been carried out. If you see any grey coloured tape, this is normally called ‘flash band’ and is used as a temporary repair. However, it is simply a sticky tape and cannot be considered permanent – the defect should be properly repaired, not just taped over!

Can you see any ‘lifted’ tiles, ones that are not lying flat? If so, there could be a problem with the roof structure beneath. Where the property is in an exposed elevation, the tiles may be vulnerable to lifting by wind and regular repairs will probably be required.

If there are a great many slipped tiles, possibly the roof is suffering from ‘nail fatigue’; the nails have started to rust away and can no longer hold the slates in place.Although such failures may occur in a localised area initially, it is highly likely to occur more widely in the near future.

Man-made regular roof ‘slates’ can be asbestos containing. They are fixed centrally with a single nail and may start to ‘ cup’ or dish. When this happens, the life span of the roof covering  becomes  very short.

Get an overview of the roof structurally

Finally, try to check the structure. Look at the condition of any mortar such as along the ridge or the hips. If the mortar is missing, this indicates lack of routine maintenance.These areas will require repairs at the very least and possibly more extensive remedial action.

Is there any ‘dishing’ to the roof covering?Do the tiles lie in a straight line? If not, this suggests an inadequacy in the roof structure beneath, possibly very costly to remedy.