How do I insulate solid walls?

[Udhi]

Hello all,
I have a 1936 built house. Builder says ALL external walls are SOLID 9" walls, no insulation. The house is incredible cold. There are damp patches on the first floor, but external render seems in good condition.

ADDITION: piccy of floor plan. North - South orientation. Kitchen is to south facing garden.

Can you please advice on INSULATION?

I am planning to strip the wallpaper and get it plastered. I have heard of ways to insulate single skin walls but am a complete dumbass when it comes to building methods (I can paint and tie my own shoelaces, to my credit, but that's it!). Before you advice Search functions, I have read and do not completely understand what to buy or specify for my builder.

I have to make a decision by the end of next week. I need advice on what to use, if plaster needs to be knocked off to bare brick before installation and if the damp wall will cause further problems with the overlay of insulation boards or wool or whatnot.

Can I take this opp to thank the board for the wealth of knowledge it has provided me with the many years I have been lurking here.

Thank You

 

[mointainwalker]

1) Why have you not put this question to your builder and asked his
advice ?
2) What's your budget ?
3) How many rooms and how big ?
4) Can you accept losing some space ?
5) Is there any existing insulation anywhere - e.g. loft ? If yes, how
much ?

 

[Udhi]

1: I have put this to my builder, and I want to make an informed decision based on all options. He was advising the use of a battened system rather than simple insulated plaster boards - this makes sense as something chunkier could be used

2: Budget is contingent on choices I get from Q1. At a top limit, I am not going to rebuild walls.

3: Semi detached house.

two major rooms ground level: 30x12 Lounge, 10x15 hall running into 14x8 Galley Kitchen. 75% of hallway wall is external and extends upwards to first floor ceiling.

Four major rooms and landing to first floor incl toilet.

Single pane, stained windows to North side, double glazing on Southside, some have become corrupt. Conservation area, cannot play around with single pane windows - I will put up a separate thread re secondary glazing, later on all are wood framed.

4: Yes, I can, because I don't want to die like Shackleton and I will if I try to live there now..... Builder estimates 7cm loss of space per wall.

5: There is minimal and rubbish insulation in the attic. It is to be changed.

The builder is currently contracted to remove ALL ceilings and reinstall new plasterboards and skim ALL walls. Any ideas here, re increasing spec of boards used and type of insulation to install appreciated. I am aware of companies selling KINGSPAN and CELOTEX "seconds" I hope to use them to get hold of rated products, hoping that reasons for being?

Thanks for the specifics, reading it, it seems to have highlighted some really good points.

 

[mointainwalker]

1) Don't understand reply. If your builder is only looking at a solution that
takes up 70 mm, then I am sure that you can get insulated pb that
thick.

Tell me what your walls are made of and I'll tell you the difference in insulation value between current and one or two alternatives.

 

[PrenticeBoyofDerry]

use the Download on the link below, it's at the bottom.
Should help you understand how it works.
You can use insulated board but still need to batten wll out, make sure the Plasterboard has a vapour check, or a vapour barrier will need to be installed.

http://www.insulation.kingspan.com/uk/k12.htm#

 

[Udhi]

mointainwalker, the builder isnt "only" looking at that. It is his recommendation. Nothing wrong with offering other, possibly better options to him. I think that is part of being communicative with him.

The walls seem to be solid brick no obvious cavity, there is a one or two inch layer of render on the outside and the same depth of plaster on the inside.

Prentice, thanks for the link. I was looking at something called K18 on the same web site. Is K18 the plasterboard with vapour barrier you were referring to?

Lets say that I wanted to control the space loss from installing this thick insulation. Can I ask for the builder to remove all the plaster on the wall right back to the brick, then install the insulation? This would cause only a 50mm loss of space rather than 70mm. OR, it might mean I can install a 100mm insualtion with only a 80mm loss of space.....Would this cause any probs with damp? Would I be asking him to install one of those Damp Proof membranes on the bricks before installing battens? Would that not mean that water will not have a chance to evaporate from the bricks making them waterlogged???! KONFUSLED!

 

[ashymoko]

is insulated render an option for you???
it is the best solution to all your problems.

 

[PrenticeBoyofDerry]

Is K18 the plasterboard with vapour barrier you were referring to?

This board does have vapour control, incorporated within it.
So Yes

 

[mointainwalker]

Assuming 25 mm of plaster and render ( doesn't matter if it's 50 mm, changes answer only very little ) your current wall has a U value of 1.8 which is catatrophic. No wonder it feels cold.


If you knock off existing plaster and use pb with 60 mm of Polystyrene bonded on it ,you will add only 50 to wall depth but improve the U value to 0.48.

With U values the smaller the better as it represents how many Watts lost.

So in this scenario you get a 300 % improvement in insulation for the loss of 50 mm. Only thing is , you would want to be very conscientious about knocking off the existing plaster so you could the dot and dab the pb /poly sheets flat onto the wall.

I don't know about insulated render values but per m2 and per cm depth,it has to be less effective and much more expensive than the pb/poly.

 

[Udhi]

Hi all,
Survived my first week at the house. It seems that it was rented and on gas meter. As predicted by the posters, the heat loss is (financially) catastrophic.

I paid 5 pounds per day, just to keep the place warm. The house temperature plummets within an hour of the CH being turned off.

I have pretty much decided on Kingspan K17 insulated plaster board at this time. Total depth incl pb is about 72mm (60mm PIR + 12mm PB). The builder is not keen on knocking off the plaster, as he foresees the walls to be uneven and needing a skim coat anyway to make things straight enough for battening and mechanically fixing K18 boards.

ASHYMOKO - Thanks for the idea on insulated external render. The house has been freshly rendered and painted outside. I am hoping not to knock it all off immediately to install the insulated render. Too much work and money at this time. BUT, definitely on the cards with increasing fuel costs.

Here are further Qs:
The walls were damp on my access to the house, left unoccupied for 6 months, no heating. The damp patches are not present now, after the house has been running heating for a week.
K17 PIR PB is a adhesive install board. Straight onto the plaster. Do you think it is ok to install this rather than batten fixation of K18? Both have vapour barriers already on boards. I understand that KINGSPAN offers tech services for decisionmaking, but I am asking your opinions.

Adhesion gives me back 25mm lost space due to a lack of battens.


COLD BRIDGES
Installation of 72mm k17 on window reveals is going to cause problems with currently installed windows. Someone suggested 12mm CELOTEX PIR (TM3000 ?) on reveals and a coat of plaster - is this still a good tactic or are you aware of better solutions? Do I have to consider Vapour barriers etc here?

LOFT SPACE
The loft space is ENORMOUS. I can stand up straight in about 40-50% floor area. About 6 foot head space. It is reasonably WARM. Forum knowledge indicates the warmth is a sign of escaping heat. There are remnants of glassfibre insulation on some parts of the floor. The majority is missing. There is NO insulation on the roof at all.

I will set up a separate thread on insulating roof spaces, PLEASE have a look in there and offer advise, if you have read this - you might have a more cohesive picture of what I am trying to do!!


Any advise is welcome, I need to buy and submit stuff to the builder by next week!![/b]

 

[mointainwalker]

If your current plaster walls are in reasonable condition, your builder probably has a good point about the need to remove plaster and then re-skim the walls.

I would guess though, he is more concerned about complications rather than the fact that knocking off, only to partly renew (skim) plaster doesn't seem like a good investment of time and therefore money to me .

if you leave the plaster as is, you sacrifice what ....? 15 mm max per wall maybe ?

Is that amount of space worth all the extra cost to you ? Your decision.


Window reveals

Are you looking to remove the plaster there and then add the insulation ?

If so I would say yes but add as much as you can without making the proportions stupid (i.e. get too close to the window ). No VB needed.

 

[ajrobb]

COLD BRIDGES
Installation of 72mm k17 on window reveals is going to cause problems with currently installed windows. Someone suggested 12mm CELOTEX PIR (TM3000 ?) on reveals and a coat of plaster - is this still a good tactic or are you aware of better solutions? Do I have to consider Vapour barriers etc here?

You have to prevent surface condensation at the reveals and you DO need a vapour barrier. The dew point must occur within vapour-proof insulation. Kingspan have drawings of reveals. I think they suggest removing existing plaster from reveals, replacing it with 25mm backed K17 plasterboard and cut away the wall insulation to fit. The insulation backing provides the vapour barrier.

 

[mointainwalker]

@ AJRobb

All types of insulating boards are impervious to moisture, no further VB is required.

The foil that is added is , I believe, a marketing measure aimed at multi-foils and to confuse the consumer.

 

[ajrobb]

The walls were damp on my access to the house, left unoccupied for 6 months, no heating. The damp patches are not present now, after the house has been running heating for a week.

K17 PIR PB is a adhesive install board. Straight onto the plaster. Do you think it is ok to install this rather than batten fixation of K18? Both have vapour barriers already on boards. I understand that KINGSPAN offers tech services for decisionmaking, but I am asking your opinions.

I am looking at a similar problem but I too am a newbie - so beware! I'm posting as much to get feedback as to offer advice.

I don't think KINGSPAN recommend adhesive fixing of K17 to external solid walls. Speaking from ignorance given a damp wall, I'd be tempted to use galvanised steel battens rather than wood. You get some insulation from the 25mm air gap, so you could probably drop from 72mm to 60mm insulation.

I am concerned that your unheated walls get damp. If you insulate the inside, your brick walls will never be heated and may become very damp. This could blow the remaining plaster and leave your plaster and insulation free-standing.

The new rendering and paint should have eliminated penetrating damp, so where is the damp coming from? Does the rendering bridge the damp course? Being in the lower part of the wall, it could be rising damp.

It sounds like a possible candidate for tanking. One disadvantage is that you have to take the floor up. The advantage is the same - you get a chance to clear away rubble, check/fix rotten joists and to insulate under the floor. You can also wrap the embedded end of the joists in polythene to keep them dry. A surveyor might suggest improving ventilation under the floor with additional air bricks.

 

[ajrobb]

@ AJRobb

All types of insulating boards are impervious to moisture, no further VB is required.

The foil that is added is , I believe, a marketing measure aimed at multi-foils and to confuse the consumer.

Thanks, but I did state that the insulation backing provides the VB. I wanted to make it clear (but failed) that using something like mineral wool in the reveal without a VB is not an option.