Aco drain to take water away from dining room wall

[AdamD]

We’ve had to replace some floor joists close to the bifold doors due to rot, twice this has happened, all other joists look absolutely fine. My feeling is it is related to the volume of rain that hits that area and collects. Had a few opinions and 2 quotes. 1 to aco drain all the way round to existing gulley and one just aco around the bifold and conservatory into a patio soakaway. Prices seem astronomical for 3-4 days work and fairly little and inexpensive materials bill. 5.4k and 4.8k.

 

thoughts on this and other options?

Edited Monday at 20:45 by AdamD

[AdamD]

First pic is the area in question second one is the side of house which does to gulley

the pic I couldn’t upload shows the front of conservatory. It’s essentially 2 right angles to get to the gully, approx 6-8m

Edited Monday at 20:55 by AdamD

[AdamD]

Edited Monday at 20:54 by AdamD

[Mr Punter]

Cheeky (expletive deleted)ers.  DIY job. What ventilation is under the floor?

[AdamD]

Suspended timber floor

[AdamD]

9 hours ago, Mr Punter said:

Cheeky (expletive deleted)ers.  DIY job. What ventilation is under the floor?

I thought that as well, but whenever one challenges it certainly amongst online trade forums, they get pelted for not understanding how the business works, overheads etc. no, I fully understand all of that but can’t wrap my head around when a days labour for such a task went to a grand. I appreciate life is hideously expensive, we’re all living it, in the uk,  but is a grand a day genuine value?

that said, drainage does seem to be a very lucrative market so perhaps it’s just market economics.

[Redbeard]

When you or your builder start talking about 'soakaways', be sure you are on the same wavelength. IIRC the PavingExpert site used to have a really good 'primer' re soakaways. Apart from anything I often see 'soakaways' (or reference to them) which don't comply with the rules re proximity to buildings, boundaries, neighbours and so on. Equally a shallow pit full of rubble may function as a soakaway for a while and then cease to do so. If you go the soakaway route get some good drawings and follow them.

 

Also, given that conservatories may be exempt from quite a lot of 'the regs' (and may also just not necessarily be built well) beware of excavating around something which may have very minimal footings. Do test-pits first. Given the extent (or lack of it) of the job and the price quoted, if it were mine I'd be looking at whether I could do it myself and do it carefully, prudently and in line with 'the rules'.

Edited Tuesday at 07:59 by Redbeard

[Spinny]

So is that some green artificial grass matting outside the bifolds ?

Internal FFL looks as though it is lower than the outside ground level under the artificial grass. And which way does the ground slope, does it have a proper fall away from the bifolds ?

I might guess rain goes through the artificial grass and pools underneath unable to runaway because of lack of slope, and the presence of the artificial grass stopping it from running away or indeed evaporating.

Maybe consider lowering the outside ground level which looks like it could well be above DPC. If you are going to have to shell out then make sure it is a proper permanent fix you are going for. (Have you got an internal step up somewhere ?)

[AdamD]

1 hour ago, Spinny said:

So is that some green artificial grass matting outside the bifolds ?

Internal FFL looks as though it is lower than the outside ground level under the artificial grass. And which way does the ground slope, does it have a proper fall away from the bifolds ?

I might guess rain goes through the artificial grass and pools underneath unable to runaway because of lack of slope, and the presence of the artificial grass stopping it from running away or indeed evaporating.

Maybe consider lowering the outside ground level which looks like it could well be above DPC. If you are going to have to shell out then make sure it is a proper permanent fix you are going for. (Have you got an internal step up somewhere ?)

Yes it’s Astro turf outside the bifolds.

It looks lower but is In fact marginally higher than outside, albeit clearly not enough.

slope - I need to run a level On it, will do

later and refer back here. Interestingly neither of the people quoting got a spirit level on it.

agree about it possibly pooling but the timber the Astro sits on seems fine which is odd.

lowering could be done but creates an issue as our main patio is level wirh the Astro, I can’t be removing 50 m square of patio and lowering it all.

no internal step up 

[Spinny]

47 minutes ago, AdamD said:

the timber the Astro sits on seems fine

What is the makeup outside then ? Do you have a timber deck under the astro ? Then concrete or earth or something under that ? Is the astro fixed down somehow or can you peel it back ?

Maybe you have some photos of before the deck and astro were put in ? Any photos of what the rotten joists looked like ? Did you have problems before they were put in ? Any air bricks down there ? Where is the DPC because ends of timber joists should be on top of DPC/DPM ? Any mold on the bottom of the wall inside or staining outside ?

 

Presumably the joists run front to back in the room behind the bifolds ?

 

I just think you need to be as certain as humanly possible about the cause in order to specify the best fix.

[AdamD]

2 hours ago, Spinny said:

What is the makeup outside then ? Do you have a timber deck under the astro ? Then concrete or earth or something under that ? Is the astro fixed down somehow or can you peel it back ?

Maybe you have some photos of before the deck and astro were put in ? Any photos of what the rotten joists looked like ? Did you have problems before they were put in ? Any air bricks down there ? Where is the DPC because ends of timber joists should be on top of DPC/DPM ? Any mold on the bottom of the wall inside or staining outside ?

 

Presumably the joists run front to back in the room behind the bifolds ?

 

I just think you need to be as certain as humanly possible about the cause in order to specify the best fix.

Timber frame around the perimeter for the Astro to be attached to, but can be peeled back carefully for inspection.

under Astro - sharp sand, then type one MOT compacted then earth.

Before Astro - per picture, decorative stones, on top of the type one MOT. Stones removed prior to Astro going down.

 

Rotten joist pics attached 

 

Yes I think there must have been as as you can see the joints were previously sistered, so clearly someone has attempted to fix them before we moved in but not the underlying issue.

 

no air brick

 

Cant See the dpm, render outside so isn’t obvious 

 

yep we have had damp marks inside the doors 

 

joists run left to right 

 

**joist pics to follow - even though they are under 2mb, the site won’t allow me to post as apparent they’re over so will try to convert them

[AdamD]

Joist pics 

Edited Tuesday at 17:15 by AdamD

[garrymartin]

8 minutes ago, AdamD said:

Site won’t let me upload <2mb pics. Any other way I can share the joist pics?

Try something like https://www.simpleimageresizer.com/ to resize the images before uploading.

[Nickfromwales]

26 minutes ago, AdamD said:

**joist pics to follow - even though they are under 2mb, the site won’t allow me to post as apparent they’re over so will try to convert them

@Sparrowhawk is currently on the case ironing out the file size upload wrinkle.
 

Bear with!  

[Spinny]

Yes those joist pics are too compressed down now to see the detail.

 

Looks a bit like ours, is it a 1930's house ?

 

We had some damp in ends of joists adjacent to our porch (see photos) but not as severe as yours. Cut the ends off worst ones, some sistering, and modified joist layout with a hanger off the other wall. Ours was due to water getting through under the porch because the ground slopes downhill towards the house at the front. We have yet to get a new outside ACO type drain in ourselves.

The original DPM directly under the joist ends was disintegrating (old bitumen felt type stuff). New DPM put in under and over the ends of the retained/sistered joists and everything treated with a boron woodworm/preservative. Nearest u/floor air vent was blocked with newspaper, which they apparently used to do in 'olden days' to try and keep warm. So cleaned that out and other bits of rubbish to improve air flow.

[AdamD]

10 hours ago, Spinny said:

Yes those joist pics are too compressed down now to see the detail.

 

Looks a bit like ours, is it a 1930's house ?

 

We had some damp in ends of joists adjacent to our porch (see photos) but not as severe as yours. Cut the ends off worst ones, some sistering, and modified joist layout with a hanger off the other wall. Ours was due to water getting through under the porch because the ground slopes downhill towards the house at the front. We have yet to get a new outside ACO type drain in ourselves.

The original DPM directly under the joist ends was disintegrating (old bitumen felt type stuff). New DPM put in under and over the ends of the retained/sistered joists and everything treated with a boron woodworm/preservative. Nearest u/floor air vent was blocked with newspaper, which they apparently used to do in 'olden days' to try and keep warm. So cleaned that out and other bits of rubbish to improve air flow.

Yeah looks similar for sure

yes 1935 is ours

 

have you addressed outside yet or as you say no aco yet so assume not? What’s your plan and route for the channels if you do? How long do you think before you have issues again ?

 

Had ours redone in April so hoping it’ll be ok given the lack of rain we’ve had but want to address it asap

 

attached photos again a bit bigger this time 

[Mr Punter]

Is the earth under the joists damp?  It needs to be completely dry.  Is there any ventilation to outside?  Ideally there should be airbricks either side and a crossflow of fresh air.  Can you rip out the timber floor, insulation and screed, or is that too disruptive?

[AdamD]

44 minutes ago, Mr Punter said:

Is the earth under the joists damp?  It needs to be completely dry.  Is there any ventilation to outside?  Ideally there should be airbricks either side and a crossflow of fresh air.  Can you rip out the timber floor, insulation and screed, or is that too disruptive?

I can’t remember to be honest, I don’t recall it being particularly damp but I may be guessing!

can’t rip out, it’s all new flooring.

 

no air brick which I think is an issue- the wall the joist butts up to in one of those pics is the adjoining  house (semi detached) so it feels like the only place for an air brick is outside the bifold but as you can see here there’s very little room 

[Redbeard]

Cross-ventilation may be your issue. One air-brick in that space won't do much. You need 'ins' and 'outs' and ideally diagonally-opposite air-bricks to ensure as much 'scavenging' of warm moist air as possible. Given how shallow that void is a solid floor might be sensible. It may even need digging out further to accommodate sufficient support and insulation.

[AdamD]

5 hours ago, Redbeard said:

Cross-ventilation may be your issue. One air-brick in that space won't do much. You need 'ins' and 'outs' and ideally diagonally-opposite air-bricks to ensure as much 'scavenging' of warm moist air as possible. Given how shallow that void is a solid floor might be sensible. It may even need digging out further to accommodate sufficient support and insulation.

I mean, the whole of the downstairs sub floor (other than kitchen area - concrete) is suspended timber floor; and there are air bricks at the direct other end (lounge) and the side of the house so I think there would be cross airflow?

We can’t rip everything up to excavate and put a new subfloor in, that’s not in our time or financial budget. Not possible.

[Mr Punter]

You can either rip it out or just leave it.  You may be able to leave it for ages without it being an issue.  As an interim measure, you could aco round the edges as you don't want any water build up in that corner.  You can get cheap stuff at about £12/m and dear stuff at £40/m.  Easy to fit.

[Spinny]

Do you have any photos of the joists after the remediation work you did was done i.e. before you put the new flooring down etc ?

 

From your photos it is tricky to see exactly how the damp was getting into the joist. The newer sister joist shows damp in the bottom 75% extending from the end through to where the bifolds are. I presume the newer joist originally reached all the way to rest on the wall but the end had completely rotted away ? Clearly the older joist was very rotten in that corner.

So

(a) it may (most likely) be that damp was reaching the joists at their ends through their bearing onto the wall. That is the bottom of the wall in the corner there and the ledge the joists sit on was getting damp. Then in the absence of any DPM between the joists and the masonry the damp was sucked into the joist ends and then down the joist length.

or

(b) it may (perhaps) be that the older joist is in contact with the masonry under the bifolds ? Or in contact with something on the possibly damp earth underneath (rags, or rubble, or timber shavings) ? Thus the older joist was getting damp and passing the damp into the newer joist by contact.

 

I presume when you did your remediation work and replaced the rotten joists that a new DPM was put along the bearer wall the joists sit on, and really ideally up the very end of the new joists too? I presume all the damp rotten wood was removed and ideally the new joists treated with preservative/wood worm treatment ? I presume the only point of contact for the new joists would be at the ends on top of new DPM and there was no direct contact anywhere else  such as under the bifold ?

 

In your photo with the torch it looks as though there may be an aperture under the floor there through the dividing wall with your neighbour ? If so there may be passage of air via such a hole. It is even possible that damp is getting into that corner area from your neighbour's side - take a look over at what is on his side - a leaky downpipe, gutter, a gully drain ? When you lift your astroturf is there any/more evidence of damp near that corner ?

 

 

Edited 15 hours ago by Spinny

[AdamD]

2 hours ago, Mr Punter said:

You can either rip it out or just leave it.  You may be able to leave it for ages without it being an issue.  As an interim measure, you could aco round the edges as you don't want any water build up in that corner.  You can get cheap stuff at about £12/m and dear stuff at £40/m.  Easy to fit.

True but easier said than done, need to channel it somewhere - soak away means removing a load of slabs, trenching and creating soak away. Into existing drain is round two right angles and on up and down levels so not that easy 

[AdamD]

1 hour ago, Spinny said:

Do you have any photos of the joists after the remediation work you did was done i.e. before you put the new flooring down etc ?

 

From your photos it is tricky to see exactly how the damp was getting into the joist. The newer sister joist shows damp in the bottom 75% extending from the end through to where the bifolds are. I presume the newer joist originally reached all the way to rest on the wall but the end had completely rotted away ? Clearly the older joist was very rotten in that corner.

So

(a) it may (most likely) be that damp was reaching the joists at their ends through their bearing onto the wall. That is the bottom of the wall in the corner there and the ledge the joists sit on was getting damp. Then in the absence of any DPM between the joists and the masonry the damp was sucked into the joist ends and then down the joist length.

or

(b) it may (perhaps) be that the older joist is in contact with the masonry under the bifolds ? Or in contact with something on the possibly damp earth underneath (rags, or rubble, or timber shavings) ? Thus the older joist was getting damp and passing the damp into the newer joist by contact.

 

I presume when you did your remediation work and replaced the rotten joists that a new DPM was put along the bearer wall the joists sit on, and really ideally up the very end of the new joists too? I presume all the damp rotten wood was removed and ideally the new joists treated with preservative/wood worm treatment ? I presume the only point of contact for the new joists would be at the ends on top of new DPM and there was no direct contact anywhere else  such as under the bifold ?

 

In your photo with the torch it looks as though there may be an aperture under the floor there through the dividing wall with your neighbour ? If so there may be passage of air via such a hole. It is even possible that damp is getting into that corner area from your neighbour's side - take a look over at what is on his side - a leaky downpipe, gutter, a gully drain ? When you lift your astroturf is there any/more evidence of damp near that corner ?

 

 

This is a great reply, I will respond tomorrow as your input is really helping me contextualise it all.

thanks