Damp in property I'm selling - got my own report - advice please

Bigphil1474

Just hoping someone could advise on some damp sorting issues on our house we're selling. I've put as much detail in as I hope you may need, queries in bold.  Just trying to gain a bit of knowledge before speaking to the damp company again.

A bit of background - we sold a couple of months ago to a FTB but he pulled out of the purchase after getting his house buyers survey back. We did get a copy of it and most of it isn't an issue (if the buyer had asked his solicitor to speak to our solicitor he could have seen copious amount of paperwork and certificates batting the issues away). One thing we couldn't cover off was damp. Now I'm fully aware that most home buying surveyors aren't great when it comes to damp, and they tend to just stick the meter on a wall and claim damp every time the meter bleeps, even though they don't work like that. However, our house is over 100 years old and a mid terrace and I do know we have some damp in the cellar and the roof has had issues over the years, so I wasn't too surprised.

Anyway, we've now sold again and we decided to get a damp and timber survey ourselves to head off any issues. Found a PCA registered company and they came out a couple of weeks ago. They'd also been sent a copy of the home buyers survey so knew what the potential issues were. The good news was that most of the damp issues in the HB survey weren't issues and the PCA guy confirmed all that at the time, and it's in the report e.g. our kitchen floor timbers aren't infested with wood worm, as per the HB survey, but we do have a small infestation of Weevil (Euphryum Confine) According to the PCA guy, not a big issue and no decay just elevated damp in cellar due to needing more ventilation, and improved ventilation will sort that out. 

They did make a number of suggestions, most of which is works they don't do themselves but gave some pretty good advice on what needs doing. The only works they've recommended which they do themselves is to install a Safeguard Dryzone DPC to the front wall of the house and around the bay area up to 1000mm (1 metre) right across the house - maybe 4-5 metres. This will involve hacking off the old plaster, installing the Dryzone DP, membrane, re-plaster, disposal of waster etc. They have quoted £2,400 plus VAT for this work. Does that sound reasonable?

Secondly, they have said that there is damp to the back of the house as the outside area is the same height as the inside and there's some penetrating damp. They said this can be solved by  either lowering the ground level outside (which will be tricky) or installing a 150mm gravel filled channel at the foot of the walls which is doable - I'm fairly handy so wondering if this is a relatively straight forward job? I know digging a 150 mm deep trench is straightforward, but do I need to line it with anything or is it just literally dig out the channel and chuck some pea gravel in? How wide should it be 15mmx15mm? The report didn't say.

Thirdly, as above the report mentioned inadequate ventilation to the cellar. We do have an airbrick but it's currently got a waste water pipe from our sump pump filling most of it so little ventilation, and needs sorting. Is it a big job to get another airbrick put in or would we better rerouting the waste pipe? We only have a half cellar under the kitchen as it is walled up halfway across so not a great deal of space to fit one in. Would we better getting mechanical ventilation put in the cellar or is a well sorted clear air brick enough? 

Thanks in advance.

stuart45

The damp proofing at the front might be unnecessary, although I suppose you will have some paperwork to show the buyers. Bay windows on older houses are often affected by condensation. If you've already got a DPC, it's unlikely to be rising damp. Even if it is rising damp the new Dry rods are easy to DIY.

Nobbie1967

This is the sort of thing you want at the back, about 6” wide. If possible, have the gravel below the existing ground level.

FreeBear

Bigphil1474 said: According to the PCA guy, not a big issue and no decay just elevated damp in cellar due to needing more ventilation, and improved ventilation will sort that out. 

They did make a number of suggestions, most of which is works they don't do themselves but gave some pretty good advice on what needs doing. The only works they've recommended which they do themselves is to install a Safeguard Dryzone DPC to the front wall of the house and around the bay area up to 1000mm (1 metre) right across the house - maybe 4-5 metres. This will involve hacking off the old plaster, installing the Dryzone DP, membrane, re-plaster, disposal of waster etc. They have quoted £2,400 plus VAT for this work. Does that sound reasonable?

Thirdly, as above the report mentioned inadequate ventilation to the cellar. We do have an airbrick but it's currently got a waste water pipe from our sump pump filling most of it so little ventilation, and needs sorting. Is it a big job to get another airbrick put in or would we better rerouting the waste pipe? We only have a half cellar under the kitchen as it is walled up halfway across so not a great deal of space to fit one in. Would we better getting mechanical ventilation put in the cellar or is a well sorted clear air brick enough?

Those Dryzone rods do little, if anything to stop damp. And slapping membranes & waterproof plaster/render on the wall just hides the problem for a few years. £2.4K for such a small amount of work is a very nice little earner for them, but darned expensive for you.

Installing a french drain (a gravel filled trench) will be much cheaper and go a long way to combat any damp - You can do that yourself if you are reasonably fit. I'd go 200mm wide and 100-150mm deep as long as the footings do not get exposed. No real need to line the trench with anything, but if you are on clay, put in a perforated land drain pipe and route it to a soakaway.

Ventilation in a cellar is good. More is better. So reroute the sump pump pipe, and fit an extra air brick or two. You should have one every 2m or 2.4m front and back.

Bigphil1474

Thanks all., I'll shop around and see if I can get the front done cheaper - would be useful to have a piece of paper to waive at the buyers in case they get jittery. Got a mate of a mate coming about the other stuff so might be able to do it all in a oner.

stuart45

Unfortunately having the paperwork often helps with a house sale. You would be paying the best part of £3,000 to get it. If you were to DIY some of it, for example go down to Wickes and buy some Dry rods, drill out and fit them, hack the plaster off, then how much would you expect to pay a plasterer to make good?
You could take photos of the work in progress and possibly get a receipt from the spread for completion of damp proofing works.

Bigphil1474

Generally agree Stuart. I wasn't planning to do the DPC work myself, just the digging out of the trench bit around the back and normal DIY type works.

This is the quote - bear in mind it's up to 1 metre height across the front of the house, which is only about 4.5m across in total including the doorway and a bay area, which is only about 70cm of wall vertically. I reckon no more than 4 or 5 square metres of plaster.

 

stuart45

The materials for the dryzone cost about £60, so I'd say that the whole job is a.lot of money. There is also the issue of whether it has been correctly diagnosed as rising damp. 

Bigphil1474

Thanks. Got a second company in and he said there was no signs of damp on the main walls, he thought the damp surveyor was just drumming up trade. He did say there was definitely some damp in the bay which is likely condensation due to cold surface and lack of ventilation (no trickles on window). He had a good look round and basically said he didn't think it needed the DryZone treatment, and even so a full kit was under £200. He has suggested removing all the plaster in the bay, fitting some internal insulation (solid walls), skim over, and be good as new - £350 all in. I'm going with that  

stuart45

Good result, and shows the value of not rushing in with the first opinions.
Rising damp issues are still being commonly misdiagnosed, even after years of bad publicity. One of the reasons why a lot of people have followed the idea that rising damp is a myth stated by a few like Jeff Howell and Peter Ward.
Chemical injection used to be a massive industry in the 70's through to the 90's.
A lot of older houses I worked on that were being gutted seemed to have damp proofing measures done as a standard job, as you would have a rewire.

FreeBear

Bigphil1474 said: He has suggested removing all the plaster in the bay, fitting some internal insulation (solid walls), skim over, and be good as new - £350 all in. I'm going with that  

That sounds incredibly cheap, even more so if there is a radiator to move out of the way first.

If you have the space, I'd suggest putting a layer of insulation under the window board to kill the cold spot that form in that area. If you have uPVC windows with a plastic sill, there should be plenty of space - After having new windows fitted here, I'm insulating the walls and putting 25mm all the way round the reveals. Gives the impression of slim line frames from the inside, and reduces the thermal losses in that area.

Just insulating under the window board isn't going to make much of a difference, but every little bit helps.