Extension brickwork - join to original?

Hoploz

I always thought it would be best to tie-in the brickwork of a new extn to the original wall of the house (rear extn)

A builder quoting said to me yesterday that it's best to butt them up against each other but not dovetail the brickwork due to it being a new concrete slab/separate foundations ie. any movement will be independent of each other.

Is this right, or is he trying to do a cheapo job?
Thanks

dursley.donkey

When I had an extension build about 10 years ago they used a kind of flexible plate. It screwed onto the existing wall and had some hinged protrusions that the new bricks tied into. That way the new wall couldn't pull away, but it could settle without putting pressure on the existing wall. I think it's not recommended to key into old brickwork.

slummymummyof3

We have done a number of extensions and brickwork ones have always been tied in via a dovetail. Blockwork extensions we have always used furfix or similar.

El_Sid_III

slummymummyof3 wrote: »

We have done a number of extensions and brickwork ones have always been tied in via a dovetail.

Very much doubt that. :rotfl:

Bungarm2001

My son's house extension has been beautifully dovetailed in. It looks so good and the new bricks match so well, you have trouble telling where the old house wall and the new one meet. Don't tell me that after time, any movement will rip them apart???

The wall just kind of follows on from the old one and will have a double glazed French doors with side windows in it, taking up most of the length.

Where the right angled wall then meets the other old house wall (bit hard to explain) this one is tied in with metal tie bars, not dovetailed in. All the internal blockwork looks like it will be attached with metal fixings/wall ties as these have all been attached already. I will post photos if I can as your comments have nolw got me worried.

27col

My sister lives in a semi detached house, and the back of the two houses are separated by a brick wall approx 6ft x 6ft and of 9" brickwork. This was tied into the back wall of the houses during construction. A wall of these dimensions is of considerable weight. However, it was on a foundation which was not quite as substantial as the house. This arrangement worked well for many years, but in the 1980's, during a very dry summer, the clay shrank and the foundation moved downward. The weight of the masonry, which was tied into the outer skin of the back of the houses, literally pulled the whole of the outer skin of bricks off. The whole outer skin of brick on both houses had to be rebuilt. None of this would have happened if the dividing wall had been free standing or had been secured by one of the joining strips already mentioned. I'm sure that the brickie thought that he was doing a good job, and I suppose that if the wall had been on a foundation of the same strength as the house he would have been right. So, Hoploz, from my experince, your builder was giving you good advice.

CGG

El_Sid_III wrote: »

Very much doubt that. :rotfl:

Am married to a bricklayer with 30 years experience.
Over the last 11 years he's done more than 100 extensions.
There are two ways of joining an extension to existing build. 'Toothing-in', refered to as dovetailing on here, or wall starters (ie. furfix). Stainless steel connectors bolted to existing with ties (attached every 3 couses of bricks) into the new bed joints on external walls. Internal block walls always use furfix or similar.
If your new extension is in line with the existing building toothing-in of the brickwork looks far better. If set back from existing, use furfix. Using wall starters when the new build is in line with existing, leaves an unsightly straight joint.
There are other considerations; are the bricks same size as the existing building. The older the building, normally the larger the bricks.
Most clients opt for toothing-in, if possible. As for cracking where they are toothed in it has never happened on extensions he has built.
Hope this info helps.

Li0nhead

Toothing in is something that would get any bricklayer blown off a newbuild site as it creates a weak point between old and new. Having said that we all do it and done right by using blue slate etc there should be no problem.

The correct way to do it these days is by using crocodile ties which are drilled into the wall so in effect the new is flush with the old not tied in.

charfield_2

After reading a lot of varying opinions on this forum and all over the internet(!), I am a little confused....we are in the process of having an extension done. After the builders went home on Friday afternoon, I came home from work and had a look at what they'd done. I was disappointed to discover that the new wall had not been tied in to the existing wall. This looks particularly ugly since it is one flat wall, but you can see it is two walls butted up against each other and the bricks are not even 'in line' from one wall to the other at all. I asked a bricklayer friend about this who said that this is not uncommon with bricks that may be 'mismatched' in terms of size. However, my uncle who is a builder says the brickwork could have been tied in (with more care and effort required on the part of our builder). I asked our builder about this and he basically echoed what my bricklayer friend had said.
I am annoyed it wasn't pointed out at the time of construction. I said it looks ugly and needs to be rendered to cover it up- is it reasonable to ask the builder to pay (towards) this? It is only single storey and about 5/6 metres wide. The roof is being put on next week. The other option- do I ask them to re-do it??? I have read lots of articles which say, despite the problems, it is possible to tie-in with the right tools and equipment.

thanks in anticipation of your answers!

Tucker

Ask him to tie it in, but expect to pay extra as it's something you needed to clarify at the outset and clearly wasn't what the builder has quoted for.

charfield_2

Will this be the cheapest option for me? I'm not against rendering- eventually we do want the whole house done as it is very mismatched- but it was something we were considering doing later rather than sooner as all our money is going towards the extension at the moment.

How much should I expect to be charged extra by the builder for tying-in (very roughly of course)? The brickwork is single-storey.

Or how much does rendering just that particular wall cost?- it's about 5/6 m wide, single storey as I said.

I know these will be very rough figures- but when you have absolutely no idea (like me) a ball-park figure is a start!

If the price difference isn't enormous, you see, I'd probably go for the tying-in option, since we then have the option to not go for the rendering at all or at least not have to look at an ugly wall until we do.

thanks very much for your advice!