Survey results- would you be overly concerned?

FreeBear

stephaniesays said:

Oh dear. If there is evidence of holes drilled in the walls, that probably means waterproof render/plaster on the inside. Rather than commissioning further surveys and/or getting an experienced contractor in, I'd suggest looking for another property. If you are wedded to the idea of a Victorian property, try to find one that hasn't been burgered around with and retains many of the original features.

Thanks! And sorry for further questions, I have no clue about this stuff! Why would you say that- is it due to the fact that you reckon this will be modern waterproof render that will trap moisture in there? (Explain it like I’m five years old if you would be so kind!). I’ll try to attach a few pics below of the render. It’s a shame really because the rest of the house is all original features, just the back of the property that’s been redone with this render. 

These salesmen will stick their damp meters in to a wall and tell you that the DPC has "failed" along the length of the wall. However, the materials used for a DPC (slate, engineering brick, bitumen, etc), if they fail, will be in isolated spots. Large scale failure is usually down to elevated ground levels, and the cure is to dig down.

When they drill holes in to the walls, it is usually above where the original DPC is. They also claim that the chemicals will magically migrate horizontally through the brick (or mortar joint) to create an impervious barrier. When challenged, they will produce a report from some "research" that they have paid for, and it will lack any peer review. A modicum of critical thinking, and you can pick holes in the testing methodology big enough to drive a bus through.

One test "report" i looked at, had the researcher place a stack of bricks in a tray of water and measure the migration of water using a series of SHTxx temperature/humidity sensors inserted in the mortar joint between each brick. The problem here is a) it is extremely rare to find walls standing in a permanent pool of water unless built next to a river. b) SHTxx sensors will only measure relative humidity levels in free air, not encased in cement.

Wrong testing methodology using inappropriate sensors. Consequently, any data collected is going to fundamentally flawed.

To cover the fact that the chemical injections don't really do much, a waterproof plaster is slapped on the wall internally. This hides the effects of damp trapped in the wall for a few years (if you are lucky, maybe 10-12 years). By the time damp reappears, the company that did the work will have gone bust and/or you find the 25 year warranty to be so full of holes as to be worthless. So you are left with the option of having another round of chemical injections and yet more waterproof plaster slapped on the walls.... Or undoing the damage as best you can by chipping off all the very hard cement inside & out and fixing the root cause of the damp. But if you have ever tried to remove cement from a brick, you'll know it will leave you with an ugly surface. And on a soft Victorian facing brick, it is quite likely that the brick will crumble in front of you. The people I know that have carried out removing of cement renders & plasters have usually had to rerender using a lime mortar to hide the damaged bricks - A very time consuming and expensive undertaking.

Going back to your surveyor's report - You mention that the chimney stack had been removed. Yet the photos show the stack in place. However, it is missing the pots that would normally sit on top. Unless steps have been taken to ventilate the flues, damp in the chimney breasts in the rooms below could be an issue. One would normally leave the chimney pots in place and fit a cowl on top to stop rain getting in but allow air to get out. If you go ahead with this purchase, I'd recommend getting a roofer (or chimney specialist) to check that there is adequate ventilation in the remains of the chimney & flues.

ReadingTim

Suggest you phone the surveyor and ask: many will feel freer to answer more honestly in conversation than they will commit to in print.