Whats wrong with a 9inch claybrick wall?

sculptor

I'm fixing up our Victorian redbrick, a mass concrete first floor extension on top of single storey redbrick caused some problems, and I have been following discussions on this site and others about breathable walls, low carbon emitting mortars, passive heat absorption, flexability and strenght etc..............
Whats wrong with a 9 inch crossbonded clay brick wall either lime plastered or drylined with sasamox / fermacell and hemp insulation?
I need to decide quickily so answers on a postcard, please.

muffler

Talk to an engineer.

sinnerboy

9 inch solid wall ( block or clay ) unrendered will admit rain penetration into the inner face so either

1. build brickfaced cavity wall or
2. rendered conc hollow block

in case of 1 -use insulation in cavity
in case of 2- use comp . insulation plasterboard dry lining

AND

As Muffler said get Sr Eng - on the face of it what you describe is structurally suspect

( PS whats the prize for this postcard comp - blue peter badge ? )

sculptor

I had to demolish the the extension and the brick structure below, the concrete was shot to bits but the brick was much sounder. It resisted side and verticial impact much more than the concrete but you could take it apart at the joints easily.
If it was a structurally unsound method why have thousands of buildings in Dublin and elsewhere stood for hundreds of years and not failed.
As for water penetration, the internal plaster has been off the remaining walls all summer (not the driest) and there is no evidence of moisture, rising damp is a different matter.
Jim

P.S.
I'm too tired, I cant think of a smart alec prize for your reply, maybe it's enough to know you are enlightening the doubters.

sinnerboy

Sorry Jim , that you did not notice the smiley in my post , intended to recpricate the "postcard" humour in your OP .

Sounds like you know what your doing anyway ( or think you do ) so good luck with your works

sculptor

Sorry Sinnerboy, I'm not trying to be a smart alec I'm genuinely curious.
How far does moisture penetrate into a brick wall?
Would a 14 inch flemish bonded wall suffice in a sheltered area in Dublin?

sculptor

O.K. Cavity wall it is.
How do I butt the new cavity wall (100mm brick 100mm cavity 100mm block) to the old 230mm solid brick without creating a cold bridge?
Or could I use 100mm brick 30mm cavity 100mm block and insulate on the inside. I was thinking of using fermacell and rock wool, It's a small area so I dont want to loose space.

Mellor

Is there existing insulation in the existing clay wall? If there is I imagine it is drylined, but it may not be.
If there is no insulation you are going to have a cold bridge anyway as the insulation won't complete the envelope, if how ever you do have insulation, it should be possible to complete the insulation envelope (through cavity or dry lining) to a decent standard. If going the drylining route, you can get around the lose of space by having a 40mm cavity, but I've done a quick sketch here and it should be possible with partial fill cavity if you prefere this method.

sculptor

There is no insulation on the origional 230 wall. Is 40mm the minimum cavity? and just dryline the inside, old and new. I was thinking of using rockwool and fermacell, or could I fill the cavity?.
Please excuse me I know this ground has been covered a thousand times but the more threads I read the more confused I become.
Thanks

Mellor

With no ionsulation on the existing there will always be a cold bridge, and its about the same bridge if its cavity or dryline. Best practice is to insulate new and old. Best way to insulate old is to dry line, and its up to you on the new, its probably easiest to dryline the lot.