Does anyone think this little air gap will cause issues?

[erol_flow]

Victorian floating floor on the ground level.

Ive battened the joists so my subfloor lays flush.

Did this to save on mm floor height so the rooms all connect at the same level and the original hearth I want higher than the floor.

So the 400mm sheep's wool insulation needs to sit just below the battens leaving a small air gap...

I've opened up air bricks below...

What do you reckon? Is it really worth me delaying this job even further to order more wool to fill the gap?? Really want to get it done!

Apparently sheep's wool is good at not retaining all the moisture so I'm thinking I should be fine, but would love to hear what anyone thinks.

Much appreciated.

 

[Cubist]

Better late than never I suppose but in my opinion any air-gap at all is better than none.

 

[erol_flow]

Better late than never I suppose but in my opinion any air-gap at all is better than none.

So you think I'll be alright? I guess its not air tight so there shouldn't really be a problem

 

[fernicarry]

If the air gap is open to the outside world then the insulation will be far less effective. Imagine putting on a down puffer jacket, but not bothering to fasten it up...

I'd be aiming to get as much of the insulation in good contact with the underside of the floor. Sheeps wool is very squashy so it will form itself around the battens. You should really also have a breather membrane below the insulation to stop air-wash.

 

[erol_flow]

If the air gap is open to the outside world then the insulation will be far less effective. Imagine putting on a down puffer jacket, but not bothering to fasten it up...

I'd be aiming to get as much of the insulation in good contact with the underside of the floor. Sheeps wool is very squashy so it will form itself around the battens. You should really also have a breather membrane below the insulation to stop air-wash.

Yeah thats a good point. For the breather membrane do you think hessian material do?

I've become slightly obsessed with using natural materials.

 

[Cubist]

I would be mindful of what the insulation below is sitting on. Ground floor, Victorian house, most likely bare earth or builders waste. If the insulation material becomes damp it will migrate to the woodwork if it cannot otherwise escape via airflow.

 

[erol_flow]

I would be mindful of what the insulation below is sitting on. Ground floor, Victorian house, most likely bare earth or builders waste. If the insulation material becomes damp it will migrate to the woodwork if it cannot otherwise escape via airflow.

There's about 2.5 ft gap to the floor which is wet ground (we're in the hills with lots of water springs) so I ran jute string in zig zags which the insulation rests on between the joists...

 

[Cubist]

Then to my mind you would not be gaining much by packing in extra insulation material at the expense perhaps of increasing the risk of moisture, drawn into the insulation material from below, transferring into the timbers of the floor.

 

[Lacan07]

Im not a fan of insulating between the joists of a suspended floor, especially if the floor is going to get damp on a regular basis.

 

[erol_flow]

Im not a fan of insulating between the joists of a suspended floor, especially if the floor is going to get damp on a regular basis.

I did read your post about this and it makes sense but unfortunately by the time I read it, it was too late, I'd already bought the stuff and since I needed the space the boxes of insulation were taking up I decided to lay it I've set up some inspection hatches so will keep an eye on things and see how we go.

I'm in a bit of a race against time to get the place livable before we have to move in so only rebuilt a section of the floating floor that was totally shot. Upon working closer with the rest I've realised it won't be long till it all needs a total rebuild which I'll probably do next year.

2 of the airbricks on the side of the wall that gets most water were cemented in, so it'll be interesting to see what it'll be like now they've been opened.

 

[fernicarry]

since I needed the space the boxes of insulation were taking up

If you just need to get rid of it then I can help you out...

I doubt hessian will work as a breather membrane, you need modern witchcraft for that. It functions like goretex, basically air and water tight but with tiny perforations that water vapour can move through.

Obviously you don't lose a massive amount of heat downwards through the floor but if the space below is well ventilated then you want to avoid that ventilation coming into the habitable spaces a.k.a drafts, hence the breather membrane. I'm part way through stapling a breather membrane below my old floorboards and so far I feel like its made a difference to comfort levels, but the gaps between some of my boards are large enough to fall through...

I've also added insulation in places but that's a much slower process since I'm doing it from below. Lots of trips up and down cutting and offering up pieces of insulation. I've held the insulation in place with strips of OSB every foot or so resting on battens. I would worry that your jute string will not last terribly long and your expensive sheep's wool insulation will soon be composting in the soil below.

 

[erol_flow]

If you just need to get rid of it then I can help you out...

I doubt hessian will work as a breather membrane, you need modern witchcraft for that. It functions like goretex, basically air and water tight but with tiny perforations that water vapour can move through.

Obviously you don't lose a massive amount of heat downwards through the floor but if the space below is well ventilated then you want to avoid that ventilation coming into the habitable spaces a.k.a drafts, hence the breather membrane. I'm part way through stapling a breather membrane below my old floorboards and so far I feel like its made a difference to comfort levels, but the gaps between some of my boards are large enough to fall through...

I've also added insulation in places but that's a much slower process since I'm doing it from below. Lots of trips up and down cutting and offering up pieces of insulation. I've held the insulation in place with strips of OSB every foot or so resting on battens. I would worry that your jute string will not last terribly long and your expensive sheep's wool insulation will soon be composting in the soil below.

I think im just going to undo the sheeps wool and use it else where. Didnt really think it through, drafts will be dealt with by the 18mm ply ive attached between joists on battens, and then the 4mm cork underlay going beneath my 9mm oak strip floor boards! Silly me, but I did get a useful video for the family reel of laying the sheeps wool which I accidently missed out on when laying upstairs.