Insulating external walls on 1940s brick home

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cannonball

28 posts

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#201309 12-Aug-2016 20:00

I need help in coming up with a feasible solution for insulating the external walls on a 1940s brick home. My wife says someone told her that we can remove the gib from the inside and then putting in batts and then re-gibbing the walls. Guess somewhat like retrofitting a weatherboard home. An installer in NZ will pump in non-formeldehyde foam as the only approved insulation option for brick homes in NZ. I am however a bit wary of this foam thing as it claims to be able to let water drain through the foam.

Any of our members have managed to insulate the external walls of their old style brick home? Would appreciate your advice. Thanks.

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#1610953 12-Aug-2016 20:15

Not a big fan of the foam. Have done it on a wooden house and was OK but was wet and the paint on the outside needed redoing as the wood expanded due to the moisture changes.

Not as good as batts as the has some gaps. But better than nothing.

I also believe some councils need consents for foam.

Have you looked at the brand website. Has options for various building types

richms

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#1610954 12-Aug-2016 20:16

How much is heating it costing you? Is the cieling already insulated the best that you can fit in there and the windows are all totally draft proofed? Not worth doing the walls till those are sorted if cost saving is your goal.

Richard rich.ms

DarthKermit

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#1610955 12-Aug-2016 20:17

I think you'd be better to remove the gib and install some kind of panel insulation like batts. There needs to be a cavity space between the insulation and the external brick wall to allow for any condensation to dissipate.

If you had holes drilled in the gib and foam insulation blown in, there's no control over where it ends up and you wouldn't be left with a cavity space either.

Ropata

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#1610957 12-Aug-2016 20:18

It's time consuming but it's something you can do your self to save money. You will need to cut Some heavy duty black building paper to shape into every frame segment leaving an air gap from frame to brick. Leave some tabs on all four sides and staple in place. You can then carefully fit Batts into each cavity. Hope this is clear but I realise it may not be. Don't go the foam route, I've seen it fail multiple times.

cannonball

28 posts

Geek

#1610960 12-Aug-2016 20:21

Yes the ceiling and underfloor are insulated maybe 4 or 5 years ago under the subsidy scheme. The windows are not double glazed and had the gaps around windows sealed as much as possible last year. I suspect there won't be any black paper in the walls either.

richms

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#1610962 12-Aug-2016 20:26

If the cieling is all done well, and you have no downlights leaking heat out and windows leaking cold draughts in, and the floor isnt crappy old boards with gaps then you have very little to gain from doing the walls. If you are planning on renovating rooms then by all means do it at the same time, but expecting to see any savings from specifically opening the walls up to insulate and then making good on it will be a net loss, other than the fact you will have nice newly gibbed walls but if the old ones look ok, no point.

Richard rich.ms

KrazyKid

1238 posts

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#1610963 12-Aug-2016 20:27

I have used a rigid product called kinspan in my current house. Instead of putting building paper and batts put this in. Still need to cut the Kingspan to size and re GiB but another option

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cannonball

28 posts

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#1610966 12-Aug-2016 20:38

How's the experience with the Kingspan product? Did it provide you with the level of insulation that you expected or did you feel the difference. How long ago have you had it installed? Cost saving is a factor but comfort is the main factor.

richms

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#1610967 12-Aug-2016 20:43

Insulation isnt a substitute for actually heating the place. What are you spending on heating at the moment?

Richard rich.ms

cannonball

28 posts

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#1610968 12-Aug-2016 20:49

I have 2 flued gas heaters, one in the dining room and another in the lounge. They are old, think they may be from the 1970s. Thinking of changing them to more modern ones too. I would expect the modern gas heaters to be more efficient. Also using the infinity gas water heater.

mattwnz

20141 posts

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#1610989 12-Aug-2016 21:58

richms:
Insulation isnt a substitute for actually heating the place. What are you spending on heating at the moment?

although a well insulated home needs less heating, so good insulation well in excess of the minimum standards is a must. Retrofitting insulation will likely require a council building consent, as it can affect the weather tightness if not done right, so would suggest talking to your council before you do anything. Especially if you plan to sell, because buyers will want to make sure it has all the relevant consents, and potentially it could cause insurance issues if you were supposed to get a consent but didn't, and say you had a fire caused by wiring in an external wall.

KrazyKid

1238 posts

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#1610999 12-Aug-2016 22:54

Probably can comment yet as I have only put kingspan in one room - working around the house slowly - and that room needs better curtains at the moment

timmmay

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#1611015 13-Aug-2016 06:19

I insulated my walls with foam, it made little difference to the temperature. Double glazing the windows made much more of a difference - cost around $14K for an average sized home, PVC. I wouldn't use foam again, it made a mess of the walls where holes were drilled and it can cause big problems with moisture.

Make sure you're not using downlights, or at least make sure they're sealed and insulated over - that will make much more difference. If you have the minimum ceiling insulation add more, I did and it makes a difference you can feel.

New heater probably not more efficient, but it might capture the heat better. Burning hydrocarbons inside isn't ideal, even if flued it probably puts some moisture inside. Heat pumps are efficient, cheap to run, but create drafts and noise - my English wife doesn't like much them, but likes them better than being cold. Central heating is something all NZ houses should have, like the UK and other cold countries. NZ is a cold country.

All in all, look at other options before doing wall insulation, and really consider other insulation types.

froob

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#1611021 13-Aug-2016 08:26

Ropata:

It's time consuming but it's something you can do your self to save money. You will need to cut Some heavy duty black building paper to shape into every frame segment leaving an air gap from frame to brick. Leave some tabs on all four sides and staple in place. You can then carefully fit Batts into each cavity. Hope this is clear but I realise it may not be. Don't go the foam route, I've seen it fail multiple times.

Lots of good advice in the posts above. With a house that has brick cladding over timber framing, it's important that the gap ("cavity") between the two doesn't get blocked with insulation. I expect that will rule out any foam option.

There is a diagram in this BRANZ Build Magazine article that shows how building paper can be folded between each stud if it is not present already, as Ropata has described.

Keep in mind that you will need building consent for insulating exterior walls, unless there is a specific exemption from your council.

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cannonball

28 posts

Geek

#1611046 13-Aug-2016 10:32

Have done a quick read of the BRANZ link. What is double skin brick? I do not know what my brick wall is. All I know is that it was built in early 1940s.

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