Tag Archive for: lofts attics

OH, GOOD, IT ALREADY HAS A NEW ROOF…

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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 !

Lofts and Attics

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Lofts and Attics

Loft spaces

You are unlikely to get access to loft spaces when doing a general viewing. It’s easy to put your foot through the ceiling below when you slip on a joist! And this will be on the vendor’s household insurance or agent’s insurance so you would not be popular. So don’t be surprised if the agent will not let you check the loft void.  Just smile, knowing we will check it thoroughly for you after you have made your offer.

However, you may be allowed to poke your head and shoulders through the access hatch, as for a homebuyer’s report. Or you may be buying a property privately.

Precautions

Checking lofts is not for the faint hearted as spiders, wasps, mice, flies and rats also make these locations their homes. If you don’t like creepy-crawlies, don’t go exploring in a strange loft!

Some of the older types of loft insulation have been known to contain asbestos. So do be careful and wear a PP3 level mask before opening any loft hatch of an older property.  And carry a torch with a long beam, as very few loft areas have lights.

There are three main aspects to consider in loft spaces:

Sarking Felt

Roofing (sarking) felt is designed to keep the roof waterproof, lying beneath the tiles. It should stick out into the gutters.

One of the best easy tests is to simply turn off any torches or lights and look to see if daylight is visible through the roof or eaves. This suggests holes in tiles and felt or detailing (finishing) problems.

If the black bitumen type felt is present, this is a much older felt.If there are large rips or tears present, it may need replacing.This is a very expensive job -say £6k+.Differing colours of felt indicate where patch repairs have been made internally. These are rarely successful and again replacement in probably necessary.

Is the felt white, blue or green coloured, with tiny dimples? This suggests that the roof has been recovered in the last 20 years with a stronger breathable type of felt and should have a long service life left. However, look for rips and tears, due to poor installation. And condensation can still cause mould growth.

Timbers

The main things to look for are split or bowing timbers in a roof structure. Cracked timbers are often very noticeable as the sharp edges and shear nature of cracks tend to draw the eye. Rafters, struts and braces can often be strengthened internally without the need for expensive scaffolds.

Where major components such as purlins have bowed, this is seldom an “easy” fix. It may have been caused by heavier replacement roof tiles, for example.  Often a new larger purlin will be required, at considerable expense.

Bowing timbers change the way that load is carried through the building. Bowed purlins and rafters do not transmit straight down at 90° and instead push outwards.This puts additional stress on the masonry. When rafters dish in this manner, it can cause” roof spread”, damaging the supporting walls below.

Keep an eye out for patches where the timbers have clearly been stained by water in the past (or at  present!) This is most likely around chimneys, where the flashing above has been damaged.  Rot may have already set in.

Insulation

With the ever-increasing cost of heating, loft insulation has been retrofitted in many homes.

Beware! Older types of insulation were vermiculite, gold shiny coloured lightweight pellets and blown cellulose which looks like tiny fragments of newspaper – which is often what they were. These types have been known to contain asbestos. If these are visible, don’t go any further into the loft – be thankful you are wearing a mask!

Sometimes the loft floors have been boarded so it is difficult to add insulation.Modern Building Regulations require 270mm of mineral fibre. This is rarely achieved as the rolls normally come in 100mm thickness so 200mm is more usual.

Sometimes the insulation has been poorly installed or has been pushed right into the eaves. Then the loft space can’t breathe or ventilate itself. Condensation then builds up inside the roof void, damaging the timbers in the unseen areas in the eaves.