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[VwBrian]

Hello, I've started a little project opening up an external ground floor wall to put a window in. The house is 1930s so got them dense heavy bricks, it's a cavity wall so need to open up both skins, the opening I've made is 850mm wide and I've used a 1200mm prestressed reinforced concrete lintel from b&q which gives me the suggested 150mm end bearings. However, since getting the lintel in I'm now question if I've used the right lintel to deal with the weight of the wall above. Any advice, guidance or suggestions would be very much appreciated as I'm freaking myself out a bit now that I should have used a bigger lintel or an RSJ.

[stoneyboy]

Hi vwbrian
Provided there are no joists for the first floor buried in the wall above your new opening you should be ok. You will still need to fit an external lintel
Regards S

[VwBrian]

Thanks Stoneboy for the response, can I ask why that would matter and how I'd know?

[stoneyboy]

Hi vwbrian,
Go upstairs and look at the floor - you may need to pull back floor covering. the direction of your floorboards will be at 90 degrees to your joists. If you have a boarded floor look for the line of fixings which will be along the joists.
Joists are a point loading so you do not want one directly above your new opening, PCC lintels are not designed for this application. Add to this the age of your property which could mean that your brickwork is laid with a weaker mortar so normal arch support does not apply.
Regards S

[VwBrian]

Gotcha, so supposing there is, what might be the solution? Or is it brick the hole back up?

[VwBrian]

Hi Stoneboy thanks again for the response, what might be the solution if I have got a joist above, a specific lintel or forget it brick it back up?

[VwBrian]

Sorry Stoneboy, wasn't being impatient, the first of the last two posts wasn't showing when I posted the second one. I've checked and the floor boards are running 90degrees to the wall so guessing my joists must run parallel to the wall with the lintel.
Anything else I should consider?

[stoneyboy]

Hi vwbrian,
No, you should be ok but don't forget to incorporate some form of cavity tray over the window itself.
Regards S

[PA Surveyors]

The cavity tray should help prevent water resting on the window frame within the inner cavity. You would also need weep holes.

Although a cavity tray can be difficult to retrospectively install. As long as the external walls are in good condition then water should get in the cavity in the first place!

[VwBrian]

Hi vwbrian,
No, you should be ok but don't forget to incorporate some form of cavity tray over the window itself.
Regards S

Sorry Stoneboy, I could have sworn I responded to your last reply, just to say thanks for your advice, nice one

[VwBrian]

The cavity tray should help prevent water resting on the window frame within the inner cavity. You would also need weep holes.

Although a cavity tray can be difficult to retrospectively install. As long as the external walls are in good condition then water should get in the cavity in the first place!

The external wall is covered by a lean to garage/utility room so isn't exposed to rain but thanks for the thought