I am currently living in a house where the previous owner converted (not very well) part of the garage to give a breakfast room. The outside wall he created by building a stud wall with an 8" gap between it and the existing outside wall, part filled it with polystyrene and 12mm plaster board.

I am wanting to change the stud wall into a thermalite wall with a 4" insulated cavity. The length of wall will be aprox 8ft by 8ft high.

How do I tie this new wall to the existing outside wall? Obviously with a new built the ties are placed in the brickwork as the wall goes up.

The existing spanwise wall was built from 4" concrete blocks straight onto the concrete garage floor. From what I can gather the floor was only built aprox 4" deep over hardcore. Do you think this floor can support the weight of a wall of this thickness measuiring 9ft wide and 8ft high? This wall is currently not load bearing.

Hi, Thanks for the reply. I have looked in screwfix but could only find the ties for creating walls perpendicular to an existing wall. I believe these are commonly known as 'firfix'.

Would you have an item code for the suggested item?

Don't know if there is a product commercially available,but it could be done by drilling holes in the mortar of existing wall,and placing metal rods (something about the size of electric arc welding rods with the flux knocked off) and insert into holes when new wall reaches same level.
As for the floor,believe 6" to be more normal,but is it reinforced or just ordinary slab ?

Big All these will work at each end of the wall but i assume ??? that the new wall is running parallel to the existing external wall and he is recreating the cavity wall but in blocks, and it is this that needs tieing in.

Diydooer dont know if it's feasible to use the screw in wall ties again available from screwfix? ???

Allo Robbo!  

Was waiting for you to say summat!

Windy

[quote author=Chaddy  link=1104741772/0#6 date=1104792778]Big All these will work at each end of the wall but i assume ??? that the new wall is running parallel to the existing external wall and he is recreating the cavity wall but in blocks, and it is this that needs tieing in.

Diydooer dont know if it's feasible to use the screw in wall ties again available from screwfix? ??? [/quote]


aaahhh got ya
just like to practice post and paste or was it paste and post as several people took ages telling me how to do it and i dont want to forget how to do it

with a 4" cavity you'll need a longer than standard tie.  I would use these:



Screw it to the existing wall as you build up the new blockwork so that they fit into the bed joints of the new wall.

Most merchants list these as "frame cramps" but they're ideal for what you want.   They come in various lengths.

Hi

Thanx everyone for your help and suggestions.

Jerry D, I mentioned the fact about the 1½ tonne car to the original building designer and he didnt seem too convinced but the wall no doubt weighs considerably less. I do realise I wont be able to build upwards any higher to create a second floor without having to dig new footings etc.

Chaddy, SFX 31633 would appear to be the correct item I am looking for as long as they will be long enough. SFX dont state the length. I will email them.

Actually a cars weight is concentrated into 4 very small areas.  An average car with 4 people in it weighs about half a tonne at each tyre.  The tyre footprint is about 0.015 sq metres which equates to a load of about 3.33 tonnes per sq  metre

This particular wall weighs about 900kgs over a footprint of 0.27 sq m.  This also equates to a load of about 3.33 tonnes per sq metre.

I agree about getting professional advice but it's not as if you're trying to build something weighing 10 tonnes.

We built some offices in a garage workshop a while back, the unit was a typical modern industrial unit with a concrete floor.  They wanted a two storey office built straight off this floor, to create a reception, cloakrooms, mot waiting bay etc with their own offices above.  The engineer asked for a test hole to be broken through the concrete slab,  This showed the floor to be 150mm thick concrete.

This was approved for the two storey build.  In addition to which they serviced and repaired commercial vehicles, there were readymix lorries, skip lorries etc all jammed in there.  The total load on that floor was enormous.  

However, it was very good concrete.