No air bricks for subfloor.

[JamesAsus]

I feel like I have been royally ****ed over in hindsight by a builder who has done my garage conversion even though at the time I was really happy with the work. The council building control officer has also been absolutely useless and hasn't mentioned multiple things I've come to find out should have been done at the time and still signed it off as 'to building regs'.

Anyway I found out I should have ventilation in the small roof void above the garage conversion (it's now a living room), I'm finding out the best way to sort that.

I've also now just come to the realisation that I have no airbricks installed for my wooden subfloor. How likely is it I'm going to run into rot issues if I don't get these installed? It seems like not many conversions actually have them but then I don't know if their subfloors are concrete whereas mine is raised timber.

The thing is the subfloor is raised timber and chipboard and has kingspan insulation in-between the joists so I don't actually see how airbricks would ventilate under here as there would be nowhere for air to flow anyway? There is a drain grate in front of the bricks where there 'should be' air bricks' so them bricks will never sit in water or anything, its an insulated cavity wall.

The subfloor sits on a concrete slab which is about 150mm lower than the rest of the house (also on a concrete slab). When a pilot hole was drilled there was found to be a vapour control barrier installed under the concrete floor.

 

[Deluks]

So this floor is completely enclosed on all sides without any ventilation? You normally need ventilation on two sides to be effective.
Not having any at all is likely to cause you problems down the line, but could be years before you notice it.

The underside of the joists will still need airflow, your vapour barrier under the concrete could be a radon barrier.

 

[freddiemercurystwin]

I don't quite understand the floor make up, are the joists suspended between the walls with a gap underneath or are the joists sat on top of the existing floor slab? In anycase it seems that a timber supported floor was the wrong floor to install, better off sticking down enough EPS insulation to bring the floor up and having the floor deck sat on top. Bit late now.

 

[JamesAsus]

I don't quite understand the floor make up, are the joists suspended between the walls with a gap underneath or are the joists sat on top of the existing floor slab? In anycase it seems that a timber supported floor was the wrong floor to install, better off sticking down enough EPS insulation to bring the floor up and having the floor deck sat on top. Bit late now.

So joists are resting on the concrete slab which is lower than the rest of the house slab. There may be a couple of mm gap between the joists and the floor as spacers were used on most of it to get the floor perfectly level. There is kingspan rigid board insulation between all the joists and then chipboard on top.

 

[freddiemercurystwin]

Well not much can be done short of ripping up the floor. I would get on with your life and forget it.

 

[martygturner]

So joists are resting on the concrete slab which is lower than the rest of the house slab. There may be a couple of mm gap between the joists and the floor as spacers were used on most of it to get the floor perfectly level. There is kingspan rigid board insulation between all the joists and then chipboard on top.

seems like every other garage conversion. And as for the ventilation that depends on the roofing membrane used under the tiles, if is permeable ie lets out water vapour then it needs nothing else.

 

[JamesAsus]

seems like every other garage conversion. And as for the ventilation that depends on the roofing membrane used under the tiles, if is permeable ie lets out water vapour then it needs nothing else.

It's not breathable membrane.

I'm really annoyed that building control didn't flag all these issues, what was the point in them if they didn't advise on anything correctly after paying them money!

 

[noseall]

It's not breathable membrane.

I'm really annoyed that building control didn't flag all these issues, what was the point in them if they didn't advise on anything correctly after paying them money!

Building Control are a checking service.
They are deffo not a 'design and babysit' service, lol.

 

[JamesAsus]

Building Control are a checking service.
They are deffo not a 'design and babysit' service, lol.

But they have 'checked' it and signed it off as compliant with building regs without advising otherwise? ......... So then what on earth is the point in them?

 

[noseall]

But they have 'checked' it and signed it off as compliant with building regs without advising otherwise? ......... So then what on earth is the point in them?

The check what they can see. If your builder has pulled a fast one, then it's the homowner that picks up the bill.
If your designer messed up, then send him a curt letter. Did you have it designed, I.e drawings etc?

 

[freddiemercurystwin]

The check what they can see. If your builder has pulled a fast one, then it's the homowner that picks up the bill.
If your designer messed up, then send him a curt letter. Did you have it designed, I.e drawings etc?

You already know the answer to that.

 

[JamesAsus]

The check what they can see. If your builder has pulled a fast one, then it's the homowner that picks up the bill.
If your designer messed up, then send him a curt letter. Did you have it designed, I.e drawings etc?

Okay then, you can VISIBLY SEE there are no airbricks in the front wall of the conversion, the bricks are not hidden, you can see the floor is timber.

So did he just not have his glasses on?

 

[freddiemercurystwin]

Correct he probably missed it. He should have but didn't. There will be no come-back to them either, they're pretty much untouchable. Unfortunately some inspectors, just like builders are not very good.

 

[JamesAsus]

Correct he probably missed it. He should have but didn't. There will be no come-back to them either, they're pretty much untouchable. Unfortunately some inspectors, just like builders are not very good.

He was genuinely useless, so annoying. The builder also should have done his job properly.

I've had work done for years by various tradesmen and always tried my best to get someone good, this time I went on personal recommendation from multiple people and STILL manage to get a job not done properly. I'm sure it will be fine for 2 years or so but then I'll have to look at pulling the carpet and chipboard up to inspect the subfloor.

 

[noseall]

You already know the answer to that.

I always advise my customers to get jobs designed. They then have a 'song sheet' we can all sing from. Always saves money in the long run.