Suspended Floor Insulation Options - Ground Floor

[robinbanks]

Tube is easier imho, the grey stuff doesn't bend but you can get self adhesive black stuff that does

 

[JohnD]

Oh one more, sorry.

For lagging i forgot to ask. Does it make a huge difference if it’s the wool wrap type or foam tube type?

View attachment 287935

Foam is a much better insulator than wool.
The Bylaws grade is thick, and best

Wool can become damp or wet and lose its insulation

The wool felt is useful for preventing pipes rubbing against floors or joists and making a noise, but not for heat insulation

 

[GeddyMortgage]

Yep, ok, foam it is then.

There is quite a lot of pipe work down there to be honest.

Is it a case that all of visible hot and cold pipes need lagging, as much as humanly possible? If so I think that’ll cost as much as the wool haha.

 

[JohnD]

You may be able to buy larger quantities at a better price from a merchant.

 

[GeddyMortgage]

OK, i'll be installing the wool through this week, so went down once again today to have a proper look around ahead of buying everything.

I noticed a few things it'd be good to get clarity on:-

Joist depths 150mm, Joist widths inconsistent (300mm -370mm)

Width - The Combi roll I bought (1140mm width) can be split into 3 lots of 380mm so i think that will be fine, presuming I can squish the 380mm into a 300mm wide gap without any issues?

Depth - With the depths at 150mm, assuming vertically compressing the 200mm roll a little bit here is also fine? Or better to let it bulge a bit if I use bird netting rather than chicken wire for example?



Location of Electrical Wires

I saw there's loads of electrical cables sagging here, there and everywhere, some were clipped to the side faces of the joists too (images below).... Again, assuming its fine to just crack on with the insulation here? or will I have to unclip these and allow them to sag beneath the insulated voids?

Also when I come across the same situation with plumbing pipes in other rooms, will the same as above apply? or different?



thanks again

 

[JohnD]

Cables can rest on top of the insulation

(Or hang beneath it)

But must not be buried in it

Looking at your pics, I think I would clip them to the underside of the joists.
If it was on top of the insulation you might put a nail tbrough it
You can clip a short bit to the side of the joist to come up through the floor.

Pipes between joists can be buried in insulation, but just push it up from underneath
If the pipes are under the insulation you will have to lag them.

It does not matter if the wool is slightly compressed

You can easily stuff quilt into a slightly narrower gap

 

[GeddyMortgage]

Perfect, thanks John. I think below will be more straight forward too. Will the same apply to any Cat5 cables too?

Gonna be a fun week!

 

[JohnD]

The insulation gap is so they don't overheat due to current passing through them

Does not apply to comms cables.

 

[JohnD]

The gas pipe does not need to be insulated, and it should exposed. I paint mine yellow, but I'm barmy.

 

[GeddyMortgage]

I believe it's disused that now anyway, was for an old gas fire that's since been removed / capped.

 

[JohnD]

IF it has been disconnected at both ends, you can remove it.

 

[robinbanks]

Will do thanks,

I read plumbing pipes should have a clearance of 100mm or so from the insulation too. So sensible just to stick to that as a rough guide?

Doesn't make sense to me; the tube shaped stuff that goes around pipes is insulation and that's a lot closer to the pipe than 100mm

Perhaps it was in relation to running pvc in polystyrene; not supposed to do it because the polystyrene damages the pvc chemically

I wouldn't bother lagging pipes that will be surrounded with wool

Width - The Combi roll I bought (1140mm width) can be split into 3 lots of 380mm so i think that will be fine, presuming I can squish the 380mm into a 300mm wide gap without any issues?

Depth - With the depths at 150mm, assuming vertically compressing the 200mm roll a little bit here is also fine? Or better to let it bulge a bit if I use bird netting rather than chicken wire for example?

width: before you unroll the roll, put a saw through the whole thing at the width you want plus a little. Let your wool expand back to its normal size on the floor befor picking it up and pushing it between joists and dont over compress it - it doesn't take much to stop it expanding back and you want it fluffed up as deep as possible

Depth: I'd let it bulge(but you can also get 170mm top up roll too. Any reasonably strong netting will be fine, doesn't have to be wire - you can get eg netting that scaffolders use to stop debris falling off scaffold fairly cheap. You might even find some scaffolding locally being taken down where the netting is being binned; they don't always reuse it.

It's usually easier (IMHO) to fit all the wool before fitting whatever holds it up permanently. I was fitting 300mm of wool between smooth joists and found I needed something to hold it up with temporarily - ended up using that nylon ribbon you tie balloons with, pushed the wool up then went side to side in a zigzag. You might find your wool stays in place by itself owing to its lower weight and the roughness of your joists

It's then easier to roll out netting and staple it up, or apply some other insulation like board or multifoil to the joist undersides. I've always considered multifoil insulations as snake oil in their claims but in this application they're quite useful, if installed properly, to go under the joists and further cut down draughts/air movement

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For your wires, it's quite convenient to staple them rather than clip them; you can get a T72 staple gun that takes staples designed for wires