Help with Wall Type & Repair Please!

thediynovice · 15 Jan 2006

The pic above (excuse the coloring - digi camera error) is of a wall underneath a window that a double-glazing firm buggered up on installing the window.

Could someone please tell me:

1) What type of wall is this? Is it plasterboard? There appears to be a thin layer of what appears to be plaster or plasterboard (it's quite cardboardy)over a greyish block (this block crumbles if you attack it with a screwdriver). The house was built in the mid eighties, if that helps.

2) What type of filler would be best to repair this?

3) Is it a concern that this "crumbly block" has cracked due to the window installation?

We've just moved into this house and this is the first time I've seen anything other tahn the normal plasterboard on wooden battens.

Many Thanks for all help provided !!!

topbanana · 15 Jan 2006

doesnt look like plasterboard though it could be the joint where board meets a different type of finish.
reading your message again says to me that the block your talking about must be a thermal block which would crumble if jabbed with a screwdriver.
so no plasterboard .
firtly get rid of anything thats loose around the crack, then fill with a filler, plaster, or whatevers in the shop.

thediynovice · 16 Jan 2006

Thanks for the reply.

I have now removed all the loose "plaster"?? from the surface and all the loose crumbly grey block, and have discovered that the crack is really deep (disappears into the wall out of sight). Is this anything to worry about?

Also, can anyone point me to a website that shows the different types of wall construction used in homes (internal and external walls) ? I've googled the phrase but can't find anything.

Thanks again for all your help.

nstreet · 16 Jan 2006

Does the crack follow the line of the blocks or does it go through the middle of the blocks. If it follows the line of the blocks, repoint and then fill and plaster over.

Is the cracking visible from outside, if so get a structural engineers opinion.

It looks as though you have had new cills installed, did you have quarry tile or similar previously. Removing these can loosen internal block work, but I wouldn't be too worried if it has, just repoint.

Prime the surface with pva or similar before filling and plastering though.

thediynovice · 16 Jan 2006

Huge thanks for the reply nstreet, really appreciated!!

Until your reply I didn't even know that they WERE blocks. Do I take it that these "blocks" have a gap between them then? The crack lines do not run in a straight line so I would guess it's through the middle of them.

Here's a better pic:

New sills WERE installed (before we moved in - we've only been in the house 2 months). They are plastic ones now. The outside of the house is rendered, and there ARE a few thin cracks in this by not in the same place as the inside. They must have been caused by the same installation.

Sorry for being a complete novice, but what do you mean by REPOINT? What do I use for that? Do I use polyfiller?

Many Thanks again!!

topbanana · 16 Jan 2006

try a search on this site for the itemsyou require helpwith. its very helpful.
its hard to comment on the reasons without seeing whats above the crack, ground conditions, recent works etc. etc
it might be worth asking your freinds,relatives etc for any good builders around or even biting the bullet and asking a building surveyor/ engineer for an informal chat perhaps.

nstreet · 16 Jan 2006

This is quite a good resource http://www.diydoctor.org.uk/projects/Pointingbrickwork.htm

This will give you some idea of how bricks a laid http://www.student.cardonald.ac.uk/materials/construction/brick bonds/index.htm

A bit on cavity walls http://www.diydoctor.org.uk/projects/cavities,cavity trays, lintels and insulation.htm

thediynovice · 17 Jan 2006

Thanks again for all your help.

Final question (honest!) :

Could I use polyfiller or that expanding foam stuff to fill the large crack in this "thermolite" type block? I am intending on skimming over the top with plaster, but don't know the best way to tackle the holes? At some points I think the crack goes right through the block.

If I should use sand/cement, can anyone tell me what quantities of each I need, and what type?

Thanks again

nstreet · 17 Jan 2006

five to one building sand to portland cement. Such a small job, just buy a bag of ready mixed from the DIY shop, you just add water. I always use one of these for pointing irregukar cracks . Push it in as deep os possible but don't fill the cavity. http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=102102&ts=99038&id=39012

Nige F · 17 Jan 2006

thediynovice said:
Thanks again for all your help.

Final question (honest!) :

Could I use polyfiller or that expanding foam stuff to fill the large crack in this "thermolite" type block? I am intending on skimming over the top with plaster, but don't know the best way to tackle the holes? At some points I think the crack goes right through the block.

Thanks again

I`d fill the crack with the contents of a tube of Resin Anchor (resin) in a mastic gun....got from Build Center..that`ll stick the block together better than when it was made.then fill over using Easifill.from same source...used for drylining wall filling....In fact I`ve done all that already.but I won`t tell where cuz someone`ll call it a bodge

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Help with Wall Type & Repair Please!

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