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Standing water in cellar and damp joists, what's the best solution?

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We have a cellar in our house in Woodseats under the living room that has water coming into it, apparently from a nearby stream. There is a sump and pump to remove excess water, but there is still standing water. We had an insulation guy come round yesterday as another problem is the house is pretty cold, but he highlighted the damp in some of the joists. One of them has 25% damp, the others are around 18-20% (I haven't checked every one). He deals with spray foam and said this would insulate the floor and allow it to breath, but I've heard conflicting things about this stuff. At the minute, there is celotex between the joists, and he said this is trapping moisture and leading to the damp.

I was thinking of putting a dehumidifer down there to try to take away some of the moisture, but I wonder whether the ingress would mean whatever water I take from the air will just evaporate from the standing water and replace it. We have an open fuel chute for ventilation (though of course that makes it cold).

The other thing to add is that there is an adjacent cellar under the dining room which you can only see through a small hole in the wall - it is mostly filled with rubble, with perhaps 3-4 ft of space under the floodboards. You can clearly see the floor hasn't been insulated there, I guess because it would be impossible for someone to access. This means the dining room floor is freezing. The insulation guy suggested filling this hole so seal off the cellar, to help prevent cold, but to me it sounds like a bad idea in terms of ventilation and damp. I haven't checked the damp levels in those joists yet (in any case I'd only be able to reach in enough to check the first one or two).

Is there some kind of expert who come come round and tell us whether the dampness in the joists is a problem, and what we could do about it? And because we originally got someone round about insulation, whether this person could also advise against this? Something we realised with the spray foam guy is people will come round to promote their own product, so we can't actually work out what is best. Any advice would be well appreciated!

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I wouldn't spray foam onto damp joists, no way, it is asking for trouble.

 

First job, is to get rid of the standing water. A de-humidifier won't do it. Have you checked the sump pump? It should be in a perforated tub, down below floor level with a float switch, so water can't get to floor level. You might need to make some channels in the floor, so it can all drain to the sump.

 

Do that first. With the coal chute ventilation should be fine. Get any rotten damp wood replaced.

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Those foam insulation guys are cowboys IMO, avoid!

 

Channel the standing water into the sump pump, with ventilation the room should start to dry out.

Edited by geared

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Cheers both, year got that impression, the guy seemed a bit slimy to be honest.

 

Ok so sump pump priority, and replace joists and hopefully rot hasn't started to set it.  We are thinking of getting a survey done on that, about 100quid it seems.

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I don't know if you wait till the room has dried out before getting the survey?  Perhaps that way you'd get a better idea if they actually do need replacement?

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Yea I was thinking that, good point.  The thing that concerns me most is the 25% damp joist and another short one I found since right at the entrance which is over 30%.  I guess if rot starts with those it could spread elsewhere, and they'll need replacing in any case (not sure at what point the damage is done).

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Surely the rot needs the moisture to progress though, so drying the place out would be the logical first step.

Then if any beams are too damaged they may need replacing, but it might depend on if rot has penetrated through.

 

Leaving it wet will cause rot though, you could probably solve the issue yourself by just creating drainage channels towards the sump pump.

Edited by geared

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As above, don't do the spray foam. 

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On 30/01/2019 at 16:35, danchill said:

Yea I was thinking that, good point.  The thing that concerns me most is the 25% damp joist and another short one I found since right at the entrance which is over 30%.  I guess if rot starts with those it could spread elsewhere, and they'll need replacing in any case (not sure at what point the damage is done).

Seasoned (ie-air dried) firewood for burning in wood burners is 20-25% moisture. Have a good poke at the joists with a  sharp screwdriver.  If it doesnt stick right in or the wood crumble I wouldnt worry.

 

If you do get somebody in to survey be careful who you use. There are loads of cowboys in the damp game.  Definitely dont use someone who also does any works needed.

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