Be your own Surveyor – Solid Internal Walls.

Be your own Surveyor – Solid Internal Walls.

I blogged about timber-frame internal walls last week, this week it’s solid internal walls. Older houses will usually have lime mortar, which is much softer but less prone to cracking (it absorbs the movement). Modern houses will have cement mortar.

Many of the same things apply as for timber walls. Use a spirit level to check door frames for level. Also look out for wallpaper crinkling diagonally at the corners where walls join indicating settlement (see last week’s blog).


Rising damp is indicated by plaster becoming loose or peeling off below about 1.2 metres high, and by ‘efflorescence’, the appearance of fine carbonate and sulphate salt crystals on the surface, which often push through the plaster. These may need injecting with a silicone-based damp-proof membrane (DPM). A typical terrace can be done for about £500 but get competitive quotes. A few older houses have a slate DPM, which has been used since the time of the Romans!

Internal walls may have become overloaded by having large sections removed, for instance to knock a lounge and diner into one. This is indicated by diagonal cracking to the sides of the opening, as the walls compress where the lintels above are carried. Lintels should be on concrete padstones with a minimum bearing of 150mm. Sadly many original works in Victorian and Edwardian houses, or DIY works uncertified by Building Control, have a lot less. I have seen Victorian houses with very undersized wooden lintels, bearing on little more than the plaster! It’s a myth that old houses are better. They’re simply the ones that haven’t fallen down in the interim. Modern houses, with proper insulation, draft- and sound-proofing, and subject to the full scrutiny of Building Control, are in my opinion the best they have ever been.

Check if there are still chimneys outside but the chimney breast has gone from the rooms below. If so, what is supporting the chimney? DIY builders sometimes remove the supporting masonry leaving two tons of bricks teetering dangerously on the party wall. You don’t want to be living in a house like this when there’s a storm! I worked on a job in London where a man died when he attempted to remove a chimney from the bottom up and it collapsed on him. Ideally the chimney should be taken right out from the top (see my blog on roofs). Failing that it can be supported on lintels between the walls to either side, or cambered out from the party wall although this is less secure.

Finally, party walls. In modern houses they should be thick enough to avoid undue  noise disturbance from next door. Older houses with two-brick thick walls plastered on both sides would normally pass modern acoustic tests. Unfortunately many older terraces only have party walls one brick thick and sound insulation is poor. Without drilling into the wall, the only way to tell is to listen when the neighbours are active and gauge how much noise there is.

I’ll write something on external walls next week.


These blogs are not intended to replace the services of a surveyor, engineer or other professional. They may however help save you the expense of a surveyor for a duff building that you won’t buy.


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