Replacing(and lowering) existing timber floor with concrete floor

[Adsibob]

5 minutes ago, TonyT said:

Stick to Mike’s book he’s the expert

I can’t see how to buy it; the website you linked doesn’tappear to sell it - or maybe it dos and I’m blind - and it’s not on amazon.

[Adsibob]

27 minutes ago, PeterW said:

Start here for some decent information about old houses

 

https://www.heritage-house.org

Thanks @PeterW. I’ve just emailed my photo to heritage house and asked if they could attend to do an urgent survey. They have an office in London, so fingers crossed they can. 

[Gus Potter]

4 minutes ago, TonyT said:

https://www.isse.org.uk/sites/default/files/2018-08/3. Rising Damp in walls - Bre.pdf
here it is for free 

 

not all SE and Architects are useless, just the pair discussing injection unicorn cream into walls.

Tony.. Was just giving you a gentle ribbing, but thanks.

 

The first part of the doc is good reading but the latter may be a bit out of date. Yes the operatives are not wearing flared trousers but the physical properties of materials have not changed since 2007 (in so far as I'm aware) .. put that caveat in as I think this may appeal.

[TonyT]

Don’t worry, I can take the banter.

[Gone West]

10 hours ago, Roger440 said:

Get a brick drop it in a bucket of water for a week, then cut it in half. I bet you its dry in the middle. Thats a week in water. But a bloke with a mastic gun is going to squirt something into you brick to make it completely waterproof in a few hours.

I watched my mates house having a silicone DPC injected back in the 70s. It wasn't ' a bloke with a mastic gun', it was a compressor pumping the liquid into the bricks under considerable pressure for quite some time. My mate didn't have a damp problem afterwards but he did a lot of work on the house and it might have been something else that solved the problem.

10 hours ago, PeterW said:

Water hasn’t seeped up the bricks. What has happened is the ground below has got wet and that will have soaked into the bricks from the sides.

In a Victorian cavity wall house I bought back in the 90s there was damp on the internal wall for about 0.5m up from the floor. The reason was the soil level was above the slate DPC. I lowered the soil level and the problem disappeared. If the water hadn't seeped up the bricks how did the wall get wet above the soil level?

 

Not being awkward, just my observations.

 

[Onoff]

You might find some useful comments here:

 

 

[PeterW]

13 minutes ago, PeterStarck said:

In a Victorian cavity wall house I bought back in the 90s there was damp on the internal wall for about 0.5m up from the floor. The reason was the soil level was above the slate DPC. I lowered the soil level and the problem disappeared. If the water hadn't seeped up the bricks how did the wall get wet above the soil level?

Usually there is no insulation and a breached DPC on the outside will allow the inside of the cavity through the mortar to become damp, and also reduce the temperature considerably inside the cavity, lowering the inner wall temperature and causing condensation to occur on the inner wall. The Heritage House link explains a lot of this and it’s interesting to read, and the science (especially the vapour pressures required) to create such a high capillary stack mean that “damp rising” is more likely to be “cold rising and condensation forming”. 

[Adsibob]

1 hour ago, Onoff said:

You might find some useful comments here:

 

 

@Onoff I did indeed find that useful. In particular this product https://www.lime.org.uk/products/sublimer-insulated-limecrete-floor.html looks like it might be much better than the concrete slab I had envisioned. 
I'll keep researching and update you all once a RICS surveyor (hopefully one trained by Pete at Heritage House) has had a look.

[DeanAlan]

@Gus Potter up for spending £15 to say £1k.

 

@Roger440 yes, EWI outside (with its own member) and then DPM lapping up the wall 600mm of so is just going to create a wall of brick tanked either side so the capillary action will suck up the water and it will not have opportunity to evaporate away given the membranes. When you say treat the building as if it doesn't have a DPC, what would that be?

 

@Adsibob hope we solve our floor lowering and damp problems. Our water table (as off two days ago and the heavy rain) about 1m below ground level but our current floor is 600m above that. I have another thread on here where I'm looking at digging a cellar below the water table which is generating some cool ideas.

 

cheers,

-Dean

[Dave Jones]

paintable DPC confirms to building regs

 

https://www.permagard.co.uk/damp-proof-paint

 

 

[Roger440]

10 hours ago, Adsibob said:

@Onoff I did indeed find that useful. In particular this product https://www.lime.org.uk/products/sublimer-insulated-limecrete-floor.html looks like it might be much better than the concrete slab I had envisioned. 
I'll keep researching and update you all once a RICS surveyor (hopefully one trained by Pete at Heritage House) has had a look.

 

Thats what im using for the floor in the old part of the cottage.

[Roger440]

10 hours ago, DeanAlan said:

@Gus Potter up for spending £15 to say £1k.

 

@Roger440 yes, EWI outside (with its own member) and then DPM lapping up the wall 600mm of so is just going to create a wall of brick tanked either side so the capillary action will suck up the water and it will not have opportunity to evaporate away given the membranes. When you say treat the building as if it doesn't have a DPC, what would that be?

 

@Adsibob hope we solve our floor lowering and damp problems. Our water table (as off two days ago and the heavy rain) about 1m below ground level but our current floor is 600m above that. I have another thread on here where I'm looking at digging a cellar below the water table which is generating some cool ideas.

 

cheers,

-Dean

 

Unless you can "fix" the DPC properly, it needs to dissipate the moisture through whatever is on the wall both sides. Ie, breathable. 

 

And dont let the drivel on modern coatings that claim to be breathable fool you. There is a measure for the breathability. Compare that number to actual lime based poducts and you will see the issue. That said, just talk to the lime guys and be guided by them.

[Roger440]

12 hours ago, PeterStarck said:

I watched my mates house having a silicone DPC injected back in the 70s. It wasn't ' a bloke with a mastic gun', it was a compressor pumping the liquid into the bricks under considerable pressure for quite some time. My mate didn't have a damp problem afterwards but he did a lot of work on the house and it might have been something else that solved the problem.

In a Victorian cavity wall house I bought back in the 90s there was damp on the internal wall for about 0.5m up from the floor. The reason was the soil level was above the slate DPC. I lowered the soil level and the problem disappeared. If the water hadn't seeped up the bricks how did the wall get wet above the soil level?

 

Not being awkward, just my observations.

 

 

It still wont soak the entire brick. Its impossible. It cant work. Unless  you house is built of sponges!

 

My house has had it done. Line off tell tale holes around the base of wall. Had zero effect. Walls are damp, inevitably. Gypsum plater inside, concrete floor with DPM undr, render painted with modern plastic paint. The perfect recipe for damp.

 

As it happens, we removed the plaster today. Sockets are 400mm up the wall. The steel back boxes are terminally rusty. The srcews holding the rads on, terminaly rusty.

 

Chemical DPC not doing whats its claimed, thats one certainty.

[Adsibob]

I heard back from Heritage House this afternoon. Unfortunately, they are fully booked for the next month and I can’t wait that long. They also wanted £1000 plus VAT which I thought was excessive given the house is in such a skeletal state following 6 days of 4 hardworking guys gutting it and exposing the foundations, that it should be quite an easy inspection for them. 

 

So instead I’m going with a chartered surveyor who has these qualifications: BSc (Hons); MSc; MMBEng; MRICS, but more importantly doesn’t like chemical injections and follows the breath-ability school of thought. I will tell him I’m quite keen on that lime company and see if he can work with them based on his findings at the property to specify something that won’t cost me any more than what the builder has quoted for before we discovered the water. 

[PeterW]

51 minutes ago, Adsibob said:

So instead I’m going with a chartered surveyor who has these qualifications: BSc (Hons); MSc; MMBEng; MRICS, but more importantly doesn’t like chemical injections and follows the breath-ability school of thought. I will tell him I’m quite keen on that lime company and see if he can work with them based on his findings at the property to specify something that won’t cost me any more than what the builder has quoted for before we discovered the water. 

Why are you telling the surveyor what materials you want to use ..? Let him make the recommendations as it’s his PI when it goes wrong or doesn’t work how you want it to. 
 

52 minutes ago, Adsibob said:

They also wanted £1000 plus VAT which I thought was excessive

That’s less than 3 days chargeable work. You lose half a day for travel, half day to inspect, day to a day and a half to write up a report and make recommendations - at £400/ day that is cheap for a surveyor, mine is on site for 20 minutes and charges £85. 

[Adsibob]

 I’m not actually going to suggest the lime product until he suggests something. I will then ask him to compare it to what he is suggesting.

 

Re the “report”, and PI insurance, in my experience these aren’t very usable as the survey report inevitably ends up being caveated extensively. If his advice turns out to be wrong, proving that to the satisfaction of an insurer, or worse still a Judge, will be very difficult indeed. I’m currently suing a fully insured damp surveyor who messed up my parents house - nightmare of a case. 

And re the idea that I have to pay people for travel time... ? I’ve never understood that. If I lived somewhere inaccesible, I might understand, but I don’t. Nobody pays me for my travel time, despite having to commute an hour each way. 

[PeterW]

I charge travel time - if I didn’t I would just wrap it up into fees and make them higher but I try and make sure things are transparent. Someone wants me to drive 3 hours across the country to look at something, why shouldn’t I charge as it’s a full day lost. 

[Adsibob]

23 minutes ago, PeterW said:

I charge travel time - if I didn’t I would just wrap it up into fees and make them higher but I try and make sure things are transparent. Someone wants me to drive 3 hours across the country to look at something, why shouldn’t I charge as it’s a full day lost. 

That’s fair enough, but this is a company which claims to have an office near to where I live. Maybe it’s just a marketing thing. 

[Onoff]

6 hours ago, Adsibob said:

I’m currently suing a fully insured damp surveyor who messed up my parents house - nightmare of a case. 

 

How many times have you sued professional services out of interest? 

 

 

[Onoff]

5 hours ago, Adsibob said:

That’s fair enough, but this is a company which claims to have an office near to where I live. Maybe it’s just a marketing thing. 

 

It often comes down to a minimum hour each way (like we charge). There's still an element of travel, having to park, parking fees etc. How close exactly are they then?

 

It's a two way street. Any professional service will charge high hourly rates etc. Useful for covering their various insurance premiums for when they do get things wrong! ?

Edited January 19, 2021 by Onoff

[Adsibob]

1 hour ago, Onoff said:

 

How many times have you sued professional services out of interest? 

 

 

I’m a litigator; it’s my job. And despite all the insurance premiums I have to pay, I don’t charge for travel time (although I know some lawyers do).

[Onoff]

26 minutes ago, Adsibob said:

I’m a litigator; it’s my job. And despite all the insurance premiums I have to pay, I don’t charge for travel time (although I know some lawyers do).

 

My brother's a barrister and he charges travel time. 

[TonyT]

I claim mileage for my personal vehicle use for work, so see no problem in this.

 

[DeanAlan]

On 18/01/2021 at 21:15, Roger440 said:

 

Unless you can "fix" the DPC properly, it needs to dissipate the moisture through whatever is on the wall both sides. Ie, breathable. 

 

And dont let the drivel on modern coatings that claim to be breathable fool you. There is a measure for the breathability. Compare that number to actual lime based poducts and you will see the issue. That said, just talk to the lime guys and be guided by them.

 

@Roger440in a prefect world, I am looking to improve the airtightness of this property as a I renovate. The extension (150% additional size) will have reasonable (beyond building regs) attention in this area and would like to bring the older part of the property up to similar level (the original 86sqm property will be basically taken back to its external walls and roof structure with replacement ground floor structure etc). 

 

If my current DPC is badly compromised (still a question really) and I am having EWI installed (which will reduce the external breathability of the solid walls to a point you made earlier) then feels like my options are narrowing in that I'm going to need to let the walls breath internally more (lime plaster?).

 

It could be the DPC is fine (I did notice, for example, that the DPC had been mortared over externally in a few places and plastered over internally and these are therefore both moisture bridges - i'll get the external ones fixed before EWI goes on) and that the dampness originated from condensation.

 

cheers,

-Dean

 

[Roger440]

8 hours ago, DeanAlan said:

 

@Roger440in a prefect world, I am looking to improve the airtightness of this property as a I renovate. The extension (150% additional size) will have reasonable (beyond building regs) attention in this area and would like to bring the older part of the property up to similar level (the original 86sqm property will be basically taken back to its external walls and roof structure with replacement ground floor structure etc). 

 

If my current DPC is badly compromised (still a question really) and I am having EWI installed (which will reduce the external breathability of the solid walls to a point you made earlier) then feels like my options are narrowing in that I'm going to need to let the walls breath internally more (lime plaster?).

 

It could be the DPC is fine (I did notice, for example, that the DPC had been mortared over externally in a few places and plastered over internally and these are therefore both moisture bridges - i'll get the external ones fixed before EWI goes on) and that the dampness originated from condensation.

 

cheers,

-Dean

 

 

If you can be sure the dpc is fixed/working, then all should be well, but id still tread carefully. 

 

My house is similar, old bit half the size of the new bit, though i didnt build it. I just accept that the downstairs part of the original house just wont be that good. Ie, no insulation on the walls, but will have in the floor (foamed glass)

 

My old 30's semi cost twice as much to heat as this, and this is twice the size. Thats despite having the flue from the wood burner (now removed) open, But it has to be or the humidity starts to climb. Basically its viable top close off the ventilation without creating other issues. I suppose i could use MHVR. But as its comfortable, and not that expensive to heat, i'll live with it.