Opening a cavity wall, and fitting a linel.

[joeb99]

Hi,

I've had a builder round to quote to cut out a hole in my wall (external wall, cavity).

The opening is to be 2100 x 1000 (or there abouts, to the nearest course of bricks)

Its a red brick house, and the outside wall is bear bricks, not rendered.

I want to know what the builder will do exactly, just out of curisity. I am not doing this my self, way too dodgy for my diy skills.

I've read up on how to fit the lintel, and from what i read, it will be a catnic type, and will be pinned up using strong boy acro props every 2ft apart.

 

[Richard C]

Thats a fairly big opening & the correct way to do it to use steel supports that pass through the wall (above where the the lintel is to be fitted) & prop these either side of the wall. Once hes got a couple of rows of bricks out & the lintel in position, he will probably use a large diamond cutting disc to slice down through the wall so be prepared for one hell of a mess!

I assume either your builder or yourself will be notifying BC? They will want to inspect the lintel installation & provision of cavity closers on the reveals & they sometimes require calculations to be submitted for the lintel!

 

[joeb99]

The builder never mentioned that!

I'll call them in the morning. - The mess will be fine, im getting used to living in a building site now.

 

[Richard C]

The builder never mentioned that!

I'll call them in the morning. - The mess will be fine, im getting used to living in a building site now.

Well many so called builders don't because they just don’t want the hassle, only your money! BC will also check they do it properly which, again, some wont like.

Unfortunately the onus is on the property owner but I think it should be the other way around because, as in your case, many don’t know about or understand the regulations & won’t even know they are supposed to do it. It should be done though as it could ultimately come back on you when you try to sell; there will be a cost involved for the BC inspection.

 

[joeb99]

The builder just left, i forgot to mention BC.

We've agreed that he will fit the lintel, and only fit the lintel - i.e. he will prop up the existing, remove 3 courses and put in the lintel. He will then put some bricks around it, and make it safe.

I will have to cut out the hole myself, which is no problem as i have a 12" petrol diamond disc cutter that i use for cutting up garden paths etc, and i will have to get rid of the old bricks (im going to use them as hardcore for a patio later in the year).


What sort of money do you recon i should be paying? Its a 2400 catnic lintel in red brick 1930s ex-council house.

 

[Richard C]

In 2005 I had two 1st floor windows moved in a gable end cavity wall; the work included cutting the new openings (1.2m x 1m approx), supply & fit new lintels, cavity closers & new DG UPVC windows & cills, making good the internal reveals & plastering. The 2 old window openings (1.5 x 1m approx) were bricked up externally (I supplied matching bricks), blocked up internally (they supplied), local cavity insulation, plastering & making good the inside walls. Total cost was £1780 but I also had to pay the cost of BC inspection; hope this helps.

 

[joeb99]

The only thing im a little worried about is the carity closers.

What are they for? and how are they fitted?

 

[Richard C]

The only thing im a little worried about is the carity closers.

What are they for? and how are they fitted?

This is typical:

http://212.100.238.60/cr/webspinner/downloads/DL78/Supafix.pdf

There are many different manufacturers but all achieve the same basic object of closing the exposed cavity & providing a moisture break between the outside brick & inside block courses (the lintel closes the top); they come in different sizes for various cavity widths & just slot into the cavity, use a few screws if they are not a snug fit.

After fitting the window, finish off by cut & stick pieces of 12mm plasterboard (use drywall or grab adhesive) around all four sides of the internal reveal (2 thicknesses if the closers are not insulated), fix a stop bead on the inside flush with the wall & against the window (or thin angle bead on the inside if your re-skimming the whole wall) & plaster over with multi-finish.

 

[joeb99]

Thanks that makes sence. So do the closers only go on the sides or on the bottom and top also? The window sill will cover the inner lower gap i guess?

Not sure what you mean by a stop bead? I intend to plaster right up to the frame with multi-finish.

 

[Richard C]

Fit the cavity closers to the 2 sides & the bottom, fit plasterboard to all 4 sides & stick the sill over that; I always use Polyboard for the sills (like laminate worktop) & a few liberal beads of trade grab adhesive is all you need to fix in place.

See here for angle & stop bead;

http://www.expamet.co.uk/bp/list2.html

If your only skimming, you will want to use 3mm, thin coat beading – it's around £1 for a 2.4m length. Use a strip of this each side of the reveals, one hard against the frame & one flush with the outside edge; plastering is then a dodle as all you have to do is run the trowel accross the 2 beads to get a perfectly flat & even plaster skim. Using angle bead on the outside of the reveal gives a perfect, sharp corner if your skimming both walls; I prefer do this even if I don’t skim the whole wall as it guarantees you wont see the join. Nails tend to crack the backing plaster & sometimes they won’t go in if you hit part of a concrete lintel or a brick so I use a couple of staples to hold it in position & then fix it more securely with grab adhesive; wait till the adhesive goes hard before plastering.
.

 

[joeb99]

Ah i see, Thanks for that!

The bulder is fitting the lintel, then im cutting out the hole, fitting the cavity closers and fitting the revels and cill, then a plasterer will deal with the beads etc.

Thanks for all your help, just waiting for the quotes to fit the lintel to come back now.


I called BC, they cost £117.50 to inspect the lintel, and need 40hrs notice.

 

[Richard C]

I called BC, they cost £117.50 to inspect the lintel, and need 40hrs notice.

Jeeez thats a lot for one lintel; it takes about 5 minutes, are you sure it's right! The price tarif should be on you council's web site.

It's a couple of years since I've been there, perhaps things have changed but both the price & notice seem excessive, they turned up the next day for me. I paid £140 for 4 inspections which include the 2 windows & lintels installed by my builder, two further lintels, drain & soil stack works for an en-suite & a final inspection; drain, soil stack & final yet to come!

 

[joeb99]

I called them, and thats what they said. I thought it was pricey, but i really dont have a choice.

They will inspect as much as you like in one sitting; so if i did loads of windows, drains etc they will check the lot all at the same time.