Insulating a solid brick wall (Internal)

[BigBigHit]

Hello there

I am renovating my 1950's added kitchen in which I will dry line the walls using metal framework. The walls are not plumb so the framework will be fixed to the concrete floor and ceiling joists. This will leave a gap of around 75mm-100mm behind the framework.

What is the best way to insulte this wall? It's a double brick wall with no cavity. I think the previous owners had problems with condensation in the past as he was using a dehumidifier. No signs of damp. I may add some velux windos at a later stage which might deal with this problem.

I have 50mm double backed Kingspan but i'm not sure if I should put it behind the frame and glue/fix directly to the wall, leave and air gap, fit a breather sheet, fit TLX silver, fit it between the framework.......God knows. There are so many theories on this subject.

I'm open to professional suggestions as I am just a DIY guy.

 

[PrenticeBoyofDerry]

http://www.nationalinsulationassoci...html?nib insulation home body=solid-wall.html
Use this link, then on menu on left click on solid wall insulation, some helpful info.

also this will help for boards
http://www.british-gypsum.com/products/plasterboard___accessories/gyproc_thermal.aspx

 

[BigBigHit]

http://www.nationalinsulationassociation.org.uk/housholder/householder-nia.html?nib%20insulation%20home%20body=solid-wall.html
Use this link, then on menu on left click on solid wall insulation, some helpful info.

also this will help for boards
http://www.british-gypsum.com/products/plasterboard___accessories/gyproc_thermal.aspx[/QUOTE]


I had a look at both those sites earlier in the week but the info is really general and not specific. Think I need something in more detail.


Thanks anyway

 

[PrenticeBoyofDerry]

Insulated dry lining can take the form of a composite 'thermal board' or a built up system using insulation behind timber battens fixed behind conventional plasterboard. For both systems the surface of the wall must be carefully prepared and all cracked or damaged plaster must be either repaired or removed. Bare brickwork or blockwork should be pointed with mortar to eliminate air paths to the exterior.

1.Thermal boards

Made of plasterboard bonded to an insulating material.

Incorporate a vapour control layer to prevent water vapour passing through the board and condensing on the cold masonry behind.

Boards are available incorporating a variety of insulants, e.g. polystyrene, polyurethane and mineral wool.

Usually 25mm - 50mm thick, with the thicker boards being the most insulating.

Should be fixed to the wall using a continuous ribbon of plaster or adhesive, and not individual 'dabs' of plaster, unless the wall is particularly uneven.

Insulation is placed between vertical stud work fixed to the wall,ceilings, floors.

A polythene sheet is fixed over the insulation and stud work beneath the plasterboards and acts as the vapour control layer.

Joint edges and services (electrical cables and wiring) which penetrate the polythene sheet must be thoroughly sealed using tape to exclude water vapour and subsequent condensation formation behind the lining.


Whichever system is installed it is very important to ensure that moisture cannot penetrate behind the plasterboard as condensation and dampness will result.

Additional insulation will be required around the sills and reveals of openings and adjacent to where internal masonry partitions meet external walls in order to prevent thermal bridging.

 

[alittlerespect]

Why would you want to leave a 75-100mm gap between the existing and the new wall?

Use 50x50 tanalised softwood and counterbatten fixing timber directly to the existing wall - I would suggest start with horizontal base and header pieces then add vertical battens at 400centres (others may have other ideas). Then fix the insulation material/plasterboard directly to the battening and skim coat of plaster to finish.

50mm insulation will provide some benefit, but if you add some additional insulation between the battening you will get some pretty impressive results.

Not sure what you mean by double-backed, but if a PIR (phenolic foam) insulation material, this has a high vapour resistivity and you will not need to worry about condensation or vapour control layer, if not PIR then add a vapour barrier before fitting insulation across the counter battening.

I should have mentioned stick the timber battens to the wall - you could use some packing pieces to straighten out the battening as you proceed, but unless it is that bad I personally would not bother, just get the plasterer to flatten out when he does his skim coat.

As for adhesives check out 'www.sika.co.uk' or email '[email protected]' they will be able to advise you on a suitable adhesive (When it comes to construction adhesives sika are the market leader and I would not compromise on this detail).

Regards

 

[tcraft]

Hi just been reading posts as this seems like the same problem I am trying to solve.
Building control want me to insulate the internal walls. From reading posts I have chosen the wooden battens fixed vertically to the walls then filled with celotex and covered with 1000 gage polythene, then plasterboard. Have spoken with celotex technical team as need to do this both upstairs and downstairs and they have said that this might not work downstairs as the property has damp problems.
Had rentokil out and they have said that its rising damp but got another company coming out for second opinion as I'm not sure it is as the property was built in 1900's and has had no central heating, just 2 electric fires and had been unoccupied for 8months before we brought it. I've had fires on for last 3 weeks and also used a de-humidifier and the walls are starting to dry out, so now not sure what to do!!!
Do you think using same method of insulation downstairs is going to increase damp issues if I get walls injected?
Really grateful for any suggestions.

 

[alittlerespect]

So, why have building control got involved?

If you do have a rising damp problem _which sounds particularly unlikely then Rentokil will only need to install a chemical dpc to solve the problem!

However, to answer your query in more detail:- It is highly likely that your real problem is condensation both surface and interstitial.

Using electric heaters would have heated the room air while they are turned on, but would have little effect on raising the temperature of the fabric elements of the building e.g. plaster/brickwork and the heat would have been lost in a relatively short period of time after turning the heaters off. Having the heaters on may have felt that they were warming the house, but in effect they were warming the air thereby allowing the warm air to hold more moisture and when the warm air meets a cold surface the air would revert to its original ability to hold less moisture and the excess would be deposited.
The condensation is caused by the warm air (which holds more moisture) being cooled and/or coming into contact with cold surfaces which causes the air to reach saturation point (dew point) and the moisture is deposited on the cold surface, the vapour can also penetrate elements of the building fabric and cause interstitial condensation.

Well that's the theory out of the way!

Next step if you are going to insulate the walls (which would be an extremely beneficial thing to do, as the right level of insulation should then make the home affordable to heat, as well as reducing your carbon footprint - I digress!) you really need to take the insulation through the ceiling voids to provide a continuous surface - a bit of hassle but well worth the effort! This should be taken up into the loft space and then the loft insulation dressed into it.
I do not go with the idea of putting loads of insulation across the ceiling as this will give rise to condensation problems within the loft space 100mm or so of roll insulation is fine, but any further insulation should take place at rafter level e.g. either between or over the top of the rafters and maintaining an air gap between the insulation and the roof structure - ideally 50mm gap but you could possibly get away with a little less - if going between the joists use a 50mm thickness insulation material preferably PIR as the condensation level to the underside of the roof covering can be quite extreme and the air gap will allow the moisture to eventually evaporate before it causes any problems.

One other area you may wish to consider is the ground floor as a lot of heat can be lost by this route - the easy solution would be to take up the flooring lay a polythene mesh over the joists then lay your insulation between the joists, personally (others may have other idea's) I would then fit a vapour barrier across the top of the joists and then relay the flooring.

Ideally you will need to use an 80mm thickness (50mm minimum to obtain any real benefit) of either polystyrene or PIR insulation material - PIR has the benefit of having a higher vapour resistance which can forgoe the need for the vapour membrane - but you must weigh up the costs of the various products. Obviously if space permits you can go beyond the 80mm thickness of insulation material but this would provide minimal additional benefit (if you care to do your sums.)

To answer your question - By insulating the walls and introducing a vapour control layer you will keep the heat and water vapour on the warm side of the structure and the issues in relation to condensation should disappear altogether.

Regards

 

[Richard C]

So, why have building control got involved?

Possibly Part L1B, changes to a thermal element; a real little beauty.

 

[tcraft]

Thanks for your advice.

Building control got involved as a neighbour complained to council as they were worried we were doing a loft conversion as I put up a fire wall (its a mid terrace house and only one side had one so I put one up in our loft while ceilings were down). When Building Inspector came round he saw that I'd removed old horse hair plaster up to a metre and told me needed to apply for building notice and would now need to upgrade the thermal elements.

Rentokil said we have rising damp in all walls and want to inject a horizontal damp proof system in mortar joints. I'm not convinced it is rising damp more like a combination of condensing and penetrating damp as in one of the rooms where old window was, outter sill had rotten because guttering had broken. Going to see what the other company say tomorrow, but not sure whether to have injection at all and just line the walls with polythene, then fix celotex then batten and plasterboard. Only worry by doin this tho is that if moisture gets in it may make its way through and cause condensation on internal walls. Building Control and Celotex Technical team both have different views so hard to know whats going to be best. Hence why I'm on computer still researching the best method!

Thanks for tips on insulation, have upgraded loft insulation both inbetween joists and horizontally.

 

[tcraft]

Yep Richard, you're right! Its been great when we only have a tiny kitchen which has already been brought and being delivered next week and you only have a about 5mm to play with then your told you need to insulate with a minimun of 65mm! Many phonecalls and tears from my wife but Building Control have been really helpful and have reduced this a bit so with a little chopping off the backs of cabinets it all should work out!

 

[Richard C]

Building control got involved as a neighbour complained to council

I hope you still sent them a Christmas card

Yep Richard, you're right!

Your not the first poor unsuspecting soul to get caught out by the 24% rule, it has come as a nasty surprise to many. I always try to warn people about this when removing plaster or render from external walls if having any BI visits even on non associated work; if your going to do it, make sure LABC don’t find out about it!

 

[Alison556]

Sorry to hijack a thread - but was looking at the link PBoD gave and they mention the Sempatap flexible lining. That looks absolutely perfect for what I want to do (insulation without too much upheaval and having to either remove or replace cornicing).

Has anyone used it? Is it as good as it sounds?

 

[alittlerespect]

Dear Alison556

The use of sempatap and the benefits to be gained would depend on the extent of the problem that you are faced with (Sempatap has a U value of 1.82 W/m2K).

The material provides some benefit (whether or not it is worth the cost of installing would be another question) however, to obtain any real improvement in insulation you would need to consider using an insulation material with a minimum thickness of 50mm. This would provide a U value of between 0.6 to 0.3 W/m2K depending on type and thickness of insulation material used.

British Gypsum do a thermaline super board which has PIR insulation finished with a plasterboard surface - the product can be simply stuck to the existing external facing walls, taped and jointed and decorated, obviously there would be a need to remove cornice/s and skirting boards, but these can be replaced on completion of the insulation works.
For example BG do a 50mm thickness board that will provide a U value of aprox 0.28W/m2K. In layman's terms that is heat losts in Watts per m2 per degree C temperature difference - C and K having the same meaning in the realms of this discussion.

For further information visit www.british-gypsum.com there are other manufactures so check out your local builders merchants for availability (that is if you are interested)!

Regards

 

[Alison556]

One of my bedrooms is absolutely freezing. It has two outside walls, one north facing the other west facing (that has the window in it). The north facing wall doesn't have mould or anything but it constantly feels damp so I'm assuming it's condensation. I don't know if the radiator is maybe not big enough to cope with the size of the room but it's never particularly "cosy" even if the heating has been on for hours (whereas the likes of the living is too hot). Even the carpet along that wall feels a bit damp. The head of the bed used to be on that wall but I had to move it because it got all mildewed.

The house was built in 1919 and is, as far as I can see, single brick (which is harled) then lathe and plaster - there is a cavity, but not the type that you can fill. Internal walls are all brick and plastered.

I've got massive foundations (apparently 10 - 13 feet deep) and got under the floor insulated last year.

I did ask in another thread about best way to insulate and we were going to baton out and use insulated plasterboard - till I read this thread and saw the Sempatap. I just wondered if that was just as good. We have cornicing and a big beam running across the ceiling and the thought of trying to get round that and replace the cornicing was a bit daunting.

 

[alittlerespect]

Just seen your latest comment - forget Sempatap!!

Regards