Reply to: loft insulation

[Halo Jones]

Miss picky... search "loft conversion & dwarf walls" to see how much it is in common useage! only by common people

Was thinking more along lines of vented soffits which are easyish to install The soffit is located in the eaves: we are talking about the same thing

Already put gable vents in (one brick size) into both voids - front & back a single brick front & back will not give you enough flow through on their own.

[lilelvis2000]

Me so confused. I' sure I typed in contractoruk.com but somehow I've ended up at B&Q forums. Though the avatars and names seem familiar.

[Troll]

That is not a dwarf wall: a dwarf wall is made of brick.. That’s why you confused me, that “wall” as you call it lateral bracing.

Posh concrete tile: ok warning here, that may be an asbestos based tile, you will only know definitively by testing (unless they have a visible maker’s reference on the underside that you can research) so worse case you do not want to be breaking or cutting any of the tiles.

Yes ventilation is best, but vents on the gable may not necessarily the most efficient solution & you may have had other influences, which is why I asked.

Ok so the point of your exercise is to make a dry storage area,

My suggestion would be, leave the membrane for now, (it was put there for a reason; it may be the main waterproofing as sarking felt may not good for that on its own), and put down your horizontal insulation & get the ventilation roof vents installed & see if that solves your problem.

You mentioned boarding the bracing: if you don’t need to do this, then don’t, as its additional loads that can block the flow of air & negate the point of ventilation.

The best combination of ventilation is a ridge & eaves, but installing the ridge vents could break tiles, which as there is an asbestos risk I would avoid.

If you can’t go for a ridge vent you can get a tile vent (best installed at the top of the roof peak on both sides)
Lastly would be some form of gable vent: this means forming an opening in the brickwork, which can be messy & then install a vent brick

The vent tiles are available in lots of styles so you should get one to match existing.

I hope that helps, I am not a building surveyor but that should be somewhere to start.

That is not a dwarf wall: a dwarf wall is made of brick.. That’s why you confused me, that “wall” as you call it lateral bracing. Miss picky... search "loft conversion & dwarf walls" to see how much it is in common useage!

Posh concrete tile: ok warning here, that may be an asbestos based tile, you will only know definitively by testing (unless they have a visible maker’s reference on the underside that you can research) so worse case you do not want to be breaking or cutting any of the tiles. OK - I've replaced a few over the years so pretty sure they have no asbestos but thanks for the heads up

The best combination of ventilation is a ridge & eaves, but installing the ridge vents could break tiles, which as there is an asbestos risk I would avoid. - Was thinking more along lines of vented soffits which are easyish to install

If you can’t go for a ridge vent you can get a tile vent (best installed at the top of the roof peak on both sides)
Lastly would be some form of gable vent: this means forming an opening in the brickwork, which can be messy & then install a vent brick

Already put gable vents in (one brick size) into both voids - front & back

I hope that helps, I am not a building surveyor but that should be somewhere to start.
Thanks...

[FiveTimes]

Hey HJ some advice please.... my property is on 3 floors with the top floor being a playroom + extra bedroom & it was built like this so not a conversion. The dwarf walls run both sides of the loft and are timber stud & uninsulated plasterboard, the roof void has insulation beneath the roof covered by a membrane - and some insulation on the floor joists - there is no ventilation in this void & I believe this makes it classed as a "warm space"

What happens is warm air condenses on the membrane and drips down onto the floor joists insulation, so I would like to remove all the insulation from under the roof, top up the floor joists to 270mm, insulate the plasterboard dwarf walls and install ventilation in the soffits and gable walls to turn this void into a "cold space"

If I remove the membrane which is a bit tatty and ripped (it has mineral wool between it & the tiles) do I have to replace it with anything or can I just leave the underneath of the roof tiles open?

I think you need a good flow of air to stop the condensation.

A couple of roof vents and some vents in the sofits but the insulation between the rafters needs a small space between roof and insulation to allow air flow.

[Halo Jones]

That is not a dwarf wall: a dwarf wall is made of brick.. That’s why you confused me, that “wall” as you call it lateral bracing.

Posh concrete tile: ok warning here, that may be an asbestos based tile, you will only know definitively by testing (unless they have a visible maker’s reference on the underside that you can research) so worse case you do not want to be breaking or cutting any of the tiles.

Yes ventilation is best, but vents on the gable may not necessarily the most efficient solution & you may have had other influences, which is why I asked.

Ok so the point of your exercise is to make a dry storage area,

My suggestion would be, leave the membrane for now, (it was put there for a reason; it may be the main waterproofing as sarking felt may not good for that on its own), and put down your horizontal insulation & get the ventilation roof vents installed & see if that solves your problem.

You mentioned boarding the bracing: if you don’t need to do this, then don’t, as its additional loads that can block the flow of air & negate the point of ventilation.

The best combination of ventilation is a ridge & eaves, but installing the ridge vents could break tiles, which as there is an asbestos risk I would avoid.

If you can’t go for a ridge vent you can get a tile vent (best installed at the top of the roof peak on both sides)
Lastly would be some form of gable vent: this means forming an opening in the brickwork, which can be messy & then install a vent brick

The vent tiles are available in lots of styles so you should get one to match existing.

I hope that helps, I am not a building surveyor but that should be somewhere to start.

[Paddy]

Looking at how much thus is going to cost, I have to wonder whether or not its worth it when my loft space is completely open to that of the adjoining property where they have no insulation at all.

I don't mind putting down some lagging but to have the required thickness would mean I'd have to use loft legs to raise the level of the floor.

Also looked at using insulation boards but they require double thickness combined with 150 mm layer of loft roll.

Then there's the polystyrene beads. Bet its a real bastard to get rid of them if you ever need to.

Anyone know any good insulation materials that are effective at a thickness of <150mm?

JHC! Don't use polystyrene beads. If there is a electrical fault; the whole house would be and inferno.

I used Mica, a blow rock fill that is fire proof. In another property I used old wool carpet felt that was given free.

[rootsnall]

Hey HJ some advice please.... my property is on 3 floors with the top floor being a playroom + extra bedroom & it was built like this so not a conversion. The dwarf walls run both sides of the loft and are timber stud & uninsulated plasterboard, the roof void has insulation beneath the roof covered by a membrane - and some insulation on the floor joists - there is no ventilation in this void & I believe this makes it classed as a "warm space"

What happens is warm air condenses on the membrane and drips down onto the floor joists insulation, so I would like to remove all the insulation from under the roof, top up the floor joists to 270mm, insulate the plasterboard dwarf walls and install ventilation in the soffits and gable walls to turn this void into a "cold space"

If I remove the membrane which is a bit tatty and ripped (it has mineral wool between it & the tiles) do I have to replace it with anything or can I just leave the underneath of the roof tiles open?

Is the 'membrane' just there to hold up the insulation !?

Any felt would normally be above the insulation, and if it was modern it would be 'breathable'. Older roofs would not normally have felt ( or other membrane ? ) at rafter level but if properly tiled that wouldn't be an issue in terms of rain getting in.

I would just whack your 270mm in at floor joist level and see if that stops the condensation by decreasing the heat in the roof void. If that doesnt work then think again and maybe put some sort of vents into the void. I'd leave the 'membrane' alone if possible and having ripping that out as your last choice.

The best option would be get someone who knows what they are talking about to take a look in person.

[Troll]

Ok some more info please:

Where are you geographically, urban, sheltered, etc
How old is the property?
You say dwarf walls: this term confuses me in this context; can you describe better, or have a photo?
The membrane, was that put in at construction or later? What is it made of & how is it fixed?
Are you changing the functionality of the space or do you just want to stop the condensation?
Is the property semi or detached?
What is the roof covering made of? (tile, slate, flat)
What influenced your thought process on venting the gable walls & soffits?

Where are you geographically, urban, sheltered, etc > Kent Urban
How old is the property? > Late 1970's trad brick & block construction


You say dwarf walls: this term confuses me in this context; can you describe better, or have a photo? tsk...really!!

The membrane, was that put in at construction or later? What is it made of & how is it fixed? at construction seems to be a tar coated(on one side) paper nailed to roof joists
Are you changing the functionality of the space or do you just want to stop the condensation? use it for storage so want to stop the drips
Is the property semi or detached? .... doesn't every successful contractor live in a 6 bed detached building
What is the roof covering made of? (tile, slate, flat) posh concrete tile
What influenced your thought process on venting the gable walls & soffits?[/QUOTE] drugs and alcohol mainly although everything I've read says venting is good

[Halo Jones]

Hey HJ some advice please....

Ok some more info please:

Where are you geographically, urban, sheltered, etc
How old is the property?
You say dwarf walls: this term confuses me in this context; can you describe better, or have a photo?
The membrane, was that put in at construction or later? What is it made of & how is it fixed?
Are you changing the functionality of the space or do you just want to stop the condensation?
Is the property semi or detached?
What is the roof covering made of? (tile, slate, flat)
What influenced your thought process on venting the gable walls & soffits?

[Troll]

Latest guidance recommends 200 - 270mm of mineral wool insulation, it would have to be a fairly hi spec (and therefore expensive) composite board (rigid board backed by foil, then high density insulation & outer skin) to achieve thermal passivity at <150mm.

Hey HJ some advice please.... my property is on 3 floors with the top floor being a playroom + extra bedroom & it was built like this so not a conversion. The dwarf walls run both sides of the loft and are timber stud & uninsulated plasterboard, the roof void has insulation beneath the roof covered by a membrane - and some insulation on the floor joists - there is no ventilation in this void & I believe this makes it classed as a "warm space"

What happens is warm air condenses on the membrane and drips down onto the floor joists insulation, so I would like to remove all the insulation from under the roof, top up the floor joists to 270mm, insulate the plasterboard dwarf walls and install ventilation in the soffits and gable walls to turn this void into a "cold space"

If I remove the membrane which is a bit tatty and ripped (it has mineral wool between it & the tiles) do I have to replace it with anything or can I just leave the underneath of the roof tiles open?

[Malcolm Buggeridge]

What strings?

As I understand it (although this could also be spreading misinformation):

- The funding comes from a government scheme.
- By taking part in the scheme suppliers are awarded carbon credits.
- The suppliers have government set targets to meet before the end of the year.
- If they fall short they are fined, hence the free offer and the deadline of 31st Dec.

Free Insulation - Home Insulation - British Gas

Loft insulation and installation - Offers - npower

Home Insulation from Tesco Home Insulation Service

Home insulation - Save and Create - Sainsbury's Energy

No strings. Just had a survey done and they said they'll do it for £150.

One has to meet certain criteria to get it free, e.g. receive benefits.

More than happy to pay that.

[Contreras]

I thought there was a scheme giving out free cavity wall and loft insulation at the moment but due to end very soon.

I looked into this once but there were strings attached.

What strings?

As I understand it (although this could also be spreading misinformation):

- The funding comes from a government scheme.
- By taking part in the scheme suppliers are awarded carbon credits.
- The suppliers have government set targets to meet before the end of the year.
- If they fall short they are fined, hence the free offer and the deadline of 31st Dec.

Free Insulation - Home Insulation - British Gas

Loft insulation and installation - Offers - npower

Home Insulation from Tesco Home Insulation Service

Home insulation - Save and Create - Sainsbury's Energy

[lukemg]

Just chucked a load of top-up mineral stuff made from recycled bottles or something from homebase, think it was 4 quid a big roll.
Made a difference but not huge as there was some already (diminishing returns).
Tried without a mask first time - not a good plan, throat irritated.
With a mask I was sweating like Mike Tyson's prom date, but worth it.
losing it through the windows I reckon, look nice in wood and DG but not a patch on upvc I had in old gaff.

[Scoi]

Just a standard fine tooth one. You can sandwich the roll between 2 planks of wood to keep the cuts relatively straight, then slide plastic off and unroll directly into place.

[Malcolm Buggeridge]

I thought there was a scheme giving out free cavity wall and loft insulation at the moment but due to end very soon.

I looked into this once but there were strings attached.