Longer lintel needed

[F]

We added a kitchen across the back of the house some years ago. Access is from the dining room through a doorway which was created by taking out a window and the wall below it.

This left the dining room a little dark so we're now thinking of widening said ex window by around a metre. Hence the need for a longer lintel.

I'm not sure if this is a d-i-y job - I really don't want a complete double-leaf gable end falling on the dining room table (it's glass!).

Anyone got any views/ideas?

Anyone got any idea of ball park cost if I got the local builder in (Leeds)?

TIA

[Rick Hughes]

If the outside skin is block & render then concrete lintels may be the simplest way .. If the wall is loadbearing then you are best using a reinforced standard lintel ... measure the opening you want add 300mm to it (150 bearing each end) that is what you need.

Not a particularly hard job to do ... done it several times, just need to use the most appropriate type of support proper to take load while you cut old lintel out.

If non-loadbearing .. then you can use a pre-stressed lintel ... about 1/3rd weight of a reinforced lintel, but you need to put a course of bricks on top for every metre of opening ... i.e. if a 3m window then you need 3 courses of bricks . The lintel & bricks work together to form as composite item.

Much easier to lift into place ... but only if non-loadbearing.

To tell if wall is load bearing one of the simple methods is to look at the joists of room above do they run at 90 degrees to wall ... is so wall is load bearing, if they run parallel, then it 'might' not be be ... depends on how roof if bearing etc.

If the outside skin is facebrick then you will need to use a catnic lintel

[F]

Both skins are brick and it's loadbearing. It was the outside wall of the house before we added the kitchen across the back.

[F]

But if both walls are now inside the house on the ground floor do I need to use a catnic? Would two RSJs do the job?

[dg]

A pre-stressed lintel IS a reinforced lintel. All concrete lintels have reinforcement in. The pre-stressing forms a chamber which is designed to flaten under load. Concrete is weak in tension and is no good on its own for supporting a load - it will crack due to shear stresses

You can use a concrete lintel for load and non-load bearing purposes, up to the designed load-bearing capacity of the lintel.

You can also use conrete for ourside skins, may not look as good, but can be used all the same.

dg

[Chris Bacon]

One would probably do... what's the span (width of new opening)?

[dg]

For double leaf walls, it may be possible to slide a lintel up - but this will require a different make to a Catnic as it should be like an upside down 'T' shape so that the upstand slots into the cavity or collar joint of a 9" wall. Catnics are 'boot' lintels and have a deep box section on the inside edge

Perhaps an IG or Keystone lintel. Then you don't have to remove courses of bricks to get the lintel in as for a Catnic, concrete lintel or RSJ.

You will need to calculate the size of an RSJ, use padstones and fire line it. Not so with a concrete lintel.

Its a straightforward job, but you just need to prop the wall above and also the floor joists if they bear onto the wall above the opening.

Oh, and this is notifiable work under the Building Regs.

Between =A3500 and =A31000 for this type of work depending on complexity

dg

[F]

1820mm, present is 820mm.

[F]

No joists onto it, just the weight of the bathroom and bedroom walls plus the loft gable end.

Bother! Or something similar...

Ouch! Presumably I can get that down somewhat by just asking for the lintel to be installed leaving me to take down the wall below and then tidy up?

[Osprey]

Yes but there is a big difference between a reinforced lintel and a pre-stressed lintel. he latter needs the composite strength of courses of brickwork. Plain reinforced lintels don't.

Pre-stressed lintels are made by having steel rope under tension then the concrete cast over them ... plain reinforced lintels have un-stressed rebar.

Why use pre-stressed ... lighter and physically much smaller than plain concrete which relies on mass for strength.

[Osprey]

nope ... you can of course use 2 RSJ's will be cheaper than catnic ... especially if you buy 2nd hand. Remember to buy expamet ... if you want to render, or noggin up and clad in plaster board