Buying a 1930s house: what to look for – wall ties, dampness, lath and plaster, textured coatings

Many people are attracted to buying a 1930s house.  Their style and accommodation often meets modern needs with larger rooms and larger gardens than their modern equivalents.  This article deals with some of the issues commonly encountered when buying a 1930s house of traditional construction.

Buying a 1930s house

1930s houses are now in the order of 80 years old.  Some may have been updated long ago and may need updating again, whilst others may not have been touched for decades.  Consequently, when buying a 1930s house there are a number of common defects to look out for.

Roofs

If you are buying a 1930s house with the original roof covering then yes, it will definitely need replacing.

If the roof covering has been replaced using reclaimed tiles then it is possible that the nibs to some of the tiles may deteriorate and lead to early failure.  It is important to check the roof slopes for any slipped tiles.  Also, check that ridge and hip tiles are adequately bedded in mortar and that hip irons are provided at the lower edges of hips to prevent slippage.

If the roof covering has been replaced then check that there is sufficient ventilation into the roof space.  If insulation is provided at ceiling level this creates what is known as a “cold roof” and the roof space will need to be ventilated to reduce the risk of condensation within the roof space.  Ventilation is often achieved with ventilation openings in the soffit.  Sometimes when additional insulation is provided at ceiling level the ventilation openings at the eaves are blocked.  This can lead to condensation (and dampness) within the roof space and this can lead to rot and/or woodworm to the roof timbers and a reduced life of the roofing felt.  Ensure that insulation does not block any ventilation openings and check for signs of rot and woodworm.  Also, ask the vendor whether any timber treatment works have been carried out and whether there is warranty.

Wall tie corrosion

In the 1930’s many houses were built with cavity walls with steel wall ties.  With cavity walls, wall ties are needed to tie the two leafs of the cavity wall together to prevent separation/bulging.   However, steel ties corrode over time.  When the steel corrodes it expands and can cause cracking to horizontal mortar joints at tie positions and in some cases bulging of the outer leaf can occur.

Corrosion of wall ties is a particular problem in coastal locations and where black ash mortar has been used.

In some instances only part of a property may be affected, eg, the side of the property facing the prevailing wind.  If wall ties are thought to be corroded then a sample of ties should be checked by a specialist wall tie contractor or an independent surveyor using a borescope (instrument used to view inside the cavity) to inspect the part of the wall ties within the cavity.  In addition to installing new ties, some wall ties will require removal to prevent further cracking as the steel ties will continue to corrode and expand if they are not removed.  If the walls are rendered externally, then re-rendering may be required after the remedial wall tie works.

Dampness

Dampness in 1930s houses can be due to a variety of causes including cavity bridging, high external ground levels, a defective or bridged damp proof course, lack of cavity trays above openings, defective rainwater goods and/or plumbing leaks.

It is important to investigate the cause of dampness so that you know what works are required and who will be the best person to employ to carry out the works.   Don’t automatically employ a damp contractor.  A damp contractor may be the right person to deal with rising dampness and timber treatment, or tanking, but if the dampness is due to an overflowing rainwater hopper then it would be better to employ a general contractor.  It is possible that there is more than one cause of dampness, e.g., lowering external ground levels may help but dampness may persist if there are other defects which may be contributing to the dampness.

Don’t confuse penetrating dampness with condensation.  If corners of rooms have mould then this could be due to condensation, particularly if the house hasn’t been heated and ventilated sufficiently and if there are areas lacking in insulation.

Also, if wall plaster contains salts this may give damp readings even if the original source of dampness has been rectified.  Salts often remain in plaster which have previously been affected by dampness and will absorb moisture from the air.  Any plaster which contains salts should be hacked off and replaced as part of any damp proofing works.

Suspended timber floors

Suspended timber ground floors require ventilation to the sub-floor void to prevent high moisture levels which can lead to rot and woodworm to timbers.  Check there are sufficient sub-floor vents and make sure they are not blocked.  If suspended timber ground floors are springy this may indicate rot and/or woodworm to the floor timbers.

If the house has an extension with a solid floor check that there is still adequate ventilation to any remaining sub-floor voids.  Depending on the configuration of the house it may have been necessary to provide ventilation via ducts through the solid floor.

If timbers are built into damp walls then they may be damp and/or rotten and/or have woodworm.

If there has been insufficient ventilation to the sub-floor void  now, or at any time previously, then there may be beetle infestation/woodworm.

When buying a 1930s house, if there are any signs of rot, woodworm and/or dampness then it is a good idea to investigate the condition of the hidden floor timbers before exchange of contracts.  It is also a good idea to get quotations for any repair works and timber treatment before exchange of contracts.

Lath and plaster ceilings

Lath and plaster ceilings are common in 1930s houses.    They are formed with a series of timber laths fixed close together.  Plaster is then applied, using the laths to form a key.  Lath and plaster ceilings can become bonded over time and fail, i.e, collapse.  Failure of lath and plaster ceilings can occur due to water damage/leakage, rot or woodworm to the timber laths, or vibration.

When buying a 1930s house, check any lath and plaster ceilings for cracks and tap at regular intervals in each room to check whether there are any hollow areas.  Replace any defective  lath and plaster ceilings with plasterboard (unless it is a Listed Building with restrictions on the ceilings).  A cheaper alternative may be to line be the underside of the ceiling with plasterboard.  Replacing ceilings is an extremely dusty and messy operation and if possible it is better to carry out this work before moving in.

Textured wall and ceiling coatings

Some textured wall and ceiling coatings (including Artex) contain asbestos.  These were widely used during the 1970s but have also been used in other decades.  If such coatings are damaged, or if are likely to be disturbed by any planned works then samples should be tested to check for asbestos content.  If works are planned to more than one area of a property then it may be necessary to take samples in a number of locations as it is possible there could be different coatings within a single property (coatings may have been applied at different times).  It is also possible that the same area of wall or ceiling has more than one layer of textured coating.

Some works to textured coatings can be carried out by non-licensed workers and may not need to be notified, whilst other works may require notification to the HSE.

Visit the Health and Safety Executive website for further information on textured coatings:

http://www.hse.gov.uk/asbestos/essentials/coatings.htm

Wiring

Even if a 1930s house has been rewired, unless this has been carried out recently the electrical installation is unlikely to meet current standards.  If you are having a survey carried out on the building then this will not include a test of the electrical installation as this is a specialist matter.  Have a qualified electrical contractor inspect and test the installation to check whether any works are required to update the installation.  Many buildings insurance policies require electrical installations to be checked at regular intervals.

Lead pipework

Check whether any parts of the water main, including any hidden areas, are lead.  Replace any lead feed pipework with potable pipework.

 

The above are some of the common issues which should be considered when buying a 1930s house.  However, this list is not exhaustive and is intended as general guidance only.  When buying a 1930s house, consider instructing a surveyor to find out the true condition of the property.

See also How much does a survey cost? and  What should I do after having a survey?

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