Sub floor ventilation help

MiniSis

Hi, new to the DIY section!

I've recently moved in to my first house. The survey notes that there wasn't any sub floor ventilation. After moving in and taking up the rank, damp carpet, some of the floorboards have rotted around the masonry.

I know that I need to fit an airbrick. However my outside patio is higher than my dining room floor. I have googled and found telescopic vents. Outside there is a concrete block with a vent in the front but no top. I've looked in it and the ground has been dug inside this block and there is a gap in the wall. I've cleared out the crap but have no idea if this goes right through.

I live on my own, first house and no idea about this kind of thing!! Do I need to get anyone round? How can I find our what the gap currently does? What do I need to fit, airbrick wise... Once done is that it? Replace the rotten boards (I think the joists need some extra support as the floor is slightly sunken in one area) and it should be fine?

Thanks in advance

teneighty

It sounds more serious than just lack of sub-floor ventilation.
If the external ground level is higher than the internal floor level there is a strong possibilty that the ends of the floor joists are rotten. You could be looking at a complete new floor and reducing the height of the external ground level.

I'm surprised that the survey did not pick up the floor levels, the dampness in the carpet and the uneven and distorted floor.

Once you've got a better idea of the extent of the damage you may want to contact the surveyor/valuer with regard to making a claim against their professional indemnity insurance.

Good Luck

MiniSis

The survey mentions higher than normal damp readings, but nothing about dmp carpet and uneven flooring. It does say about digging the patio to allow for the ventilation.

Who would be the best builder type person to get round?

MiniSis

I also had a damp survey (two) that didn't pick this up aswell.

MiniSis

I think the survey has covered their backs sufficiently! Just got to deal with ftb naivity, unfortunately. Just possibly a bigger job than I anticipated, but have people to help with the work

teneighty

Initially just remove the rotten floorboards and maybe lift 1 or 2 others so you can see the ends of the joists and any internal sleeper walls under the floor.

Then try to push a screwdriver (not something sharp like a knife) into the joists. If the wood is hard you are fine, if the screwdriver sinks in...hello Mr Rot. If you are not happy to do that yourself either a friend or a small general builder or carpenter would only need an hour to do the investigation.

If two damp surveys as well as the initial survey/valuation didn't pick this I suspect it isn't a problem, I doubt they all would have missed it.

Fingers crossed that it is just the ventilation issue.

MX5huggy

If you want to fix this permanently I would install a solid floor.

Rip out the floor 100 to 150mm of concrete install 300mm of expanded polystyrene and then screed maybe putting underfloor in the screed.

Long term you will save.

Mr_Ted

This sounds much more serious than just a lack of ventillation!

I feel whoever has done the surveys has skimped on the job and I would certainely approach them if they did it as part of the house purchase as this could affect your home insurance!

I would contact someone as a duff report has obviously been carried out and whoever did it may be liable as when you pay a so called professional you expect a professional job!

Speak to your solicitor as this could turn out to be a major expense!

Sounds to me like rising damp, damp course problems or even ingress of water!

MiniSis

Hmmm thanks all for your advice! Very differing opinions! Obviously difficult as you can't see what I can!!

In your opinion who would be the best person to get round to have a look?

The joists aren't rotten, just the ends that fit in to the wall and only where they are in contact with brick. I know for a fact that for at least 8 years (possibly longer) no Maintenence has been done in the house, so these floors will just have been left to rot. As there is no ventilation at all I do suspect that to be the problem (at the moment) although I could be wrong, but the damp is only localised to areas of masonry and nowhere else.

As for a concrete floor... How big a job would this be and how much? Thanks

gmgmgm

Concrete/solicitors probably OTT. teneighty seems spot on.
Get some ventilation (airbrick or three) in there and replace the timber which needs to be replaced.
It's already lasted 8 years so it can't be too bad.

MiniSis

Had a mate round to have a look, he had a feel an said the vent in the garden (where the patio has been dug out) is blocked, so first thing is to get the floorboard up and have a look and clear it. Then rebuild with a proper airbrick.

It does only have one airbrick (the wall is only 1.5m) as has had an extension on the back where kitchen is with concrete floor) so the current vent is in the middle of that wall.

Then I'll get all the boards up and clear underneath if there has been a build up of soil etc, get the joists fixed and replace the rotten boards.

Hopefully that will be enough... I plan to leave the boards exposed for the time being so I guess I can keep an eye on it for a year or so.

Does this sound like a plan? Apologies if I sound quite rubbish!! Single lady in my first house (a doer upper at that!!)