House / undercroft insulation questions.

[Paul_B]

We took out carpets this year and since the floorboards are so good got it polished and treated. Looks good but we're finding it feels noticeably colder. Since it's a bungalow above a garage one side and undercroft on the other where the underlying bedrock rises up. The garage end is actually warmer than the less volume undercroft.

So we're planning on insulating under the floor. Thinking very simply done with rolls of rockwool between the beams with wire mesh holding it up. It's a storage area but that wool and mesh to hold it shouldn't make it unusable for storage. Is this a good idea? It seems a cheap and easy option. Slab is general more expensive.

Also, I saw a video where they did similar with slab but used plastic sheet above the insulation with it extending down the sides against the beams. I'm guessing it's a vapour barrier. Is this needed or recommended?

I know this isn't bushcraft but I know there's some very practical and knowledgeable people on here who I reckon know a big about DIY and even building matters. So I hope someone will spare some time to reply.

 

[Toddy]

Spray foam insulation is all the rage around here.

Once it dries off it's pretty much fuss free apparently. Easy to squirt into awkward corners, safe near electrics, etc., not so appealling to rodents or insect infestations either.
Check your mortgage provider first though, there are problem with condensation on the underside of roof tiles/slates in some areas.

I would think that since you're 'under' insulating though....

 

[TeeDee]

We took out carpets this year and since the floorboards are so good got it polished and treated. Looks good but we're finding it feels noticeably colder. Since it's a bungalow above a garage one side and undercroft on the other where the underlying bedrock rises up. The garage end is actually warmer than the less volume undercroft.

So we're planning on insulating under the floor. Thinking very simply done with rolls of rockwool between the beams with wire mesh holding it up. It's a storage area but that wool and mesh to hold it shouldn't make it unusable for storage. Is this a good idea? It seems a cheap and easy option. Slab is general more expensive.

Also, I saw a video where they did similar with slab but used plastic sheet above the insulation with it extending down the sides against the beams. I'm guessing it's a vapour barrier. Is this needed or recommended?

I know this isn't bushcraft but I know there's some very practical and knowledgeable people on here who I reckon know a big about DIY and even building matters. So I hope someone will spare some time to reply.

I work for an UFH and renewables company.

Two things will have an effect upon the heat loss of the room - the thermal structure and materials ( as you say , installing Rockwool ) the second being ACR - Which is Air Change Rate - draughts , ventilation , gaps etc.

You need to address both aspects.

 

[slowworm]

But older houses are designed with drafts, i.e. air bricks and air flow to stop wooden boards and joists from rotting.

I will have a similar problem, so interested to hear of solutions, bjt would be concerned about sealing damp in and how to exclude vermin.

 

[TeeDee]

But older houses are designed with drafts, i.e. air bricks and air flow to stop wooden boards and joists from rotting.

I will have a similar problem, so interested to hear of solutions, bjt would be concerned about sealing damp in and how to exclude vermin.

Designed with draughts maybe quite a overly enthusiastic way to cover up a multitude of building sins.
I do like older houses - my last renovation was a large Victorian terrace that had plenty of thermal problems and an ACR that was 'blowy'.

That also had some 'designed' ventilation points and after a recce or two of getting under the house down on my belt buckle and inch worming along I'm not convinced that they were actively doing much.

I'm not sure about the Spray foam suggestion, I have a feeling that will lead to some inherent issues.

I guess what I am saying is , of the floorboards were anything like my own - there will be lots of gaps that need to be filled with wadding and stained to match the floor - thus limiting ACR robbing the thermal aspect.


It would be interesting to know the volume of the undercroft and how one accesses it ??

 

[Paul_B]

Half height door to get in and I'm bent double by the door but the ground rises up towards the back. A foot high or so at the back and at least a metre high at the door end. We have bikes easily fitting it almost near the back so it's probably mostly a metre high for most of it. The coldest end of the room above is at the back end with the least floor to ceiling in the undercroft.

At the other end of the house is the garage which feels warm when you open the garage door so despite carpets in the room above it is losing heat to the garage. However that room doesn't feel cold. Perhaps the carpet is stopping the acr or drafts.

I thought the guy we got in would use the dust from sanding to pack the gaps out with glue and dust to colour match. I'd read that's best practise in that job. But he didn't. Not sure what we can do now but I reckon insulation should help.

 

[TeeDee]

Half height door to get in and I'm bent double by the door but the ground rises up towards the back. A foot high or so at the back and at least a metre high at the door end. We have bikes easily fitting it almost near the back so it's probably mostly a metre high for most of it. The coldest end of the room above is at the back end with the least floor to ceiling in the undercroft.

At the other end of the house is the garage which feels warm when you open the garage door so despite carpets in the room above it is losing heat to the garage. However that room doesn't feel cold. Perhaps the carpet is stopping the acr or drafts.

I thought the guy we got in would use the dust from sanding to pack the gaps out with glue and dust to colour match. I'd read that's best practise in that job. But he didn't. Not sure what we can do now but I reckon insulation should help.

How well fitted is the door in the undercroft? Is it obvious that there are gaps or does it look as good as it may get.

 

[Stew]

Do you have access to a thermal camera?

You may have a local library of things that has one.

This is part of my loft yesterday - helped me realise I need to get some insulation right in the very end between wall and joist!!

Cracks and gaps in the floorboards can be filled from below to save you trying to colour match and re polish.

If your joists are a good standard from joist to joist I would be more tempted by PIR. What is the approx width? You need to think on the comfort of doing the work. Too narrow and stapling mesh in place will be hard work. Too wide and you’ll need to be adding cross supports for your mesh.

 

[Stew]

This looks like a good way to go:

A Best Practice Approach To Insulating Suspended Timber Floors

Fintan from our Technical Team discusses the thermal loss issues associated with suspended timber floors and outlines a best practice approach to tackling them.

www.ecologicalbuildingsystems.com

 

[Paul_B]

With access from below only a modified version will need to be used.

 

[Toddy]

So, if I'm reading that correctly; they use a semi-permeable membrane, a windblock, under the floor, then insulation, and if necessary something to cover and protect that which is also breathable, and they recommend sealing the soil beneath to stop damp coming up. It all then needs sealed tightly against the corners, edges, etc.,

I'm reading this thread with interest.
We have two vent pipes that run up inside the house in chases. The recent snow has shown very clearly that we are losing a lot of heat from those chases, enough to melt the snow on the roof by about a metre square around both....the thing is that both those corners of the house are perishing cold, and since one is the downstairs loo, at this time of year it's rather uncomfortable. The other runs behind the washing machine and up through the upstairs bathroom....which is also pretty blooming cold.
So, we were trying to figure out how to insulate the bottom of the chases, which are open to the foundations beneath. The chases (built from 3/4" plywood) are also where our water pipes run (stainless steel would you believe ? it was a thing in the 1970's when this house was built) and we have no external drain pipes apart from the rones.
The pipes inside are lagged, but there's a lot of empty space in the chases. I used to have to keep the cat out of the one behind the washing machine, he slipped in while I had the hatch open to deal with the stop cock.
I heard him scrabbling up at the ceiling one day, so there's space enough for a big tom cat to climb inside beside the pipes, and that pretty much makes these chimneys I reckon.
Lot of draught in a chimney.

Any suggestions gratefully received.

M

 

[Stew]

So, if I'm reading that correctly; they use a semi-permeable membrane, a windblock, under the floor, then insulation, and if necessary something to cover and protect that which is also breathable, and they recommend sealing the soil beneath to stop damp coming up. It all then needs sealed tightly against the corners, edges, etc.,

I'm reading this thread with interest.
We have two vent pipes that run up inside the house in chases. The recent snow has shown very clearly that we are losing a lot of heat from those chases, enough to melt the snow on the roof by about a metre square around both....the thing is that both those corners of the house are perishing cold, and since one is the downstairs loo, at this time of year it's rather uncomfortable. The other runs behind the washing machine and up through the upstairs bathroom....which is also pretty blooming cold.
So, we were trying to figure out how to insulate the bottom of the chases, which are open to the foundations beneath. The chases (built from 3/4" plywood) are also where our water pipes run (stainless steel would you believe ? it was a thing in the 1970's when this house was built) and we have no external drain pipes apart from the rones.
The pipes inside are lagged, but there's a lot of empty space in the chases. I used to have to keep the cat out of the one behind the washing machine, he slipped in while I had the hatch open to deal with the stop cock.
I heard him scrabbling up at the ceiling one day, so there's space enough for a big tom cat to climb inside beside the pipes, and that pretty much makes these chimneys I reckon.
Lot of draught in a chimney.

Any suggestions gratefully received.

M

It’s hard to diagnose without seeing but at a most basic level, is it a draught or an insulation issue?
What’s the access like?
Again, I would suggest the thermal camera route! It makes it a lot simpler to see the cold!

 

[Toddy]

I think it's a draught issue. It's pulling air up from the foundations.....which have air bricks built in.

Somehow it's also pulling warmth enough from the house to melt the snow on the roof.
All of the 4apts in the street have this same issue. You can see this so clearly while the snow is everywhere else.

My friend refuses to use her downstairs loo all Winter long.
Two others who have 'renovated' their houses and fitted new toilets, etc., fitted in heated towel rails, and their loos are still cold, as are the corners where the washing machines are plumbed in.

We're trying to work out how to stop the chimney effect but not cause any problems with damp not moving out of the foundations.

 

[TLM]

Put a plastic pipe inside the chase that takes the air from foundations and block the rest. Depending on how much moisture there is in the ground the base ventilation does not have to be all that much.

 

[Paul_B]

Where can you get thermal imaging camera / rent one from?

 

[TeeDee]

Where can you get thermal imaging camera / rent one from?

Flir i7 Thermal Imaging Camera hire

The Flir i7 is a revolutionary thermal imaging camera. It is incredibly easy to use and requires no former experience.

www.jewson.co.uk

Probably worth renting and arranging to check out friends families properties at the same time and split the cost.

 

[TLM]

"Flir" brand from eur 550 to 800. Have played with one, worked well on short range, say upto 10m. Did not have a change for testing it longer range.

 

[Stew]

Or if you’re lucky enough to have one close by

library of things thermal camera - Google Search

 

[Paul_B]

Saw this one for about £175. At this price it's not too many days rental for it to pay for itself. The cheapest rental cost I've seen is £75 plus VAT for one day's rental.