Expan' Foam or cement? Gaps around moved Lintel? Pics +movie

[Safety First]

Hi All,

Untitled

• Safety First
• 6 Dec 2014
• 1

Film!... https://www.dropbox.com/s/vu30ptxcgj0no85/Main Porch.AVI?dl=0

Q's. First, background below- if needed?

1. I am hoping that I could get away with using expanding foam instead of pointing (with mortar) in order to:

a. stop the draughts- used a jos-stick to observe ++ air being drawn into the house, around the beam.

b. stop the beam and masonry moving any further.

As in the film, it's clear that the long stones laid over the beam are spot loading it, where/how the original mortar has gone is anyone's guess? It would be a real P.I.TA to push mortar into the gaps. I am sure expanding foam would fully/deeply enter the gap and so spread loads better, or is this just not what exp' foam is good for..?

2. If i cut and fit celotex between joists over front room ceiling, do I need to leave an air-gap (inc some air flow) between ceiling/laths and celotex?

Would rockwool be a better mix of insulating with vapour movement included?


3. With some spare expanding foam and spare celotex is there harm in 'dob and dabb' style a sheet of insulation against the masonry?



Background:.............

1930s Semi. Front elev' single skin. Natural stone over brick skin. I was sure there was a void until I looked down from eaves and saw it (really) was single skin.

Bedroom above porch very draughty from under skirting.

Today found that wood lintel has kicked out from below on LHS by about 10mm, and about 10mm in opposite directon on RHS- it's twisted?

It looks like they made a deep beam by bolting a pair of beams together with spacers. The inner most lintel is visible from indoors under floorboards. Perhaps the external beam could be bolted to inner one, to stop it twisting-kicking out further?

Any thoughts please? I am hoping to set about this tomorrow!

 

[theprinceofdarkness]

What is the history? Its a rubbish job, but if its been there for over 5 years and the internal plaster is not cracking, I would not fret about the low standard of construction. Remember that lintel is only holding up a few hundredweight of bricks between it and the upstairs window.
Foam is good for draft proofing and heat insulation not for reinforcing lintels. I am not sure that you could adequately seal all the cracks with foam. I would attempt to smear a layer of mortar/plaster/filler over the lot for draft proofing. Then just stuff the whole void with glass fibre.
Frank

 

[Safety First]

Thank you very much for your time and input..

What is the history? Its a rubbish job, but if its been there for over 5 years and the internal plaster is not cracking, I would not fret about the low standard of construction.

The history- I think I'm the first in the void since 1930 and no there's no sign inside of movement.. 'Rubbish job'- yes the masons slung the stones in clearly aware that it would not be seen under porch. Other masonry in the house looks fine, where 'on show'.

Remember that lintel is only holding up a few hundredweight of bricks between it and the upstairs window.

I didn't think of that.. thanks!

Foam is good for draft proofing and heat insulation not for reinforcing lintels. I am not sure that you could adequately seal all the cracks with foam.

I am thinking otherwise, I am not best at pointing, seems to jam up in gaps and I can suspect it's not getting into full depth. The nozzle of the foam can be squashed very thin and drawn along inside a crack. I know it's awful; being an expanding foam specialist!

I would attempt to smear a layer of mortar/plaster/filler over the lot for draft proofing.

If then, you think that the load-spreading/securing goal can be put secondary to the draughtproofing, i'll prob go for foam? I'm a bit lazy and can gun foam in from front of bay- long arms! Pointing will mean crawling into the void

Then just stuff the whole void with glass fibre.

Glass fibre- is this your gen preference, or is the point about airflow really better dealt with using fibre over board insulation? Admittedly it will be much easier, but I have some celotex in the shed and no glass wool...

 

[theprinceofdarkness]

The Cellotex, which needs to be cut accurately and the problem is to fit it air tight wise against that rough old wall. A good theoretical way would to be to "glue" it on with expanding foam, but this is extremely unpredictable and is likely to blow the Cellotex of on a bubble of hardened foam. the problem is that you want to insulate two faces the wall face and the top of the ceiling, hence my suggestion of mass filling with glass fibre.
An alternative would be to insulate under the tiled roof section with your Cellotex, so as make the void come inside the house, but the triangular ends would have to be done as well. It could be done but will be very time consuming and the temptation to use foam as a gap filler must be resisted as it can easily lift the tiles.
Frank