lintel question

[ADENCOOL]

hello, im thinking about extending the rear of my property, by about 1.2m deep, by a total length of about 8 meters

the house was built approx 1986, and is detached

what is concerning me is the lintels, as i will need a lintel approx 7.8 m in length and i only want to support this at 100mm at each end, about at 100mm 1/3 of the along, is this feasibly?

(i want to do this as if i need a deep support depth, it will ruin the design of the two extended room if i need two supports at either end of the building

extension

• ADENCOOL
• 8 Oct 2010
• 2

 

[RonnyRaygun]

If you take away the rear wall of your house, you will lose the element that gives the rear of your house its lateral stability against wind loads and notional horizontal forces.
This is the reason that either steel columns are used, or a pier is left intact - usually around 600mm each end.

We would usually design an opening such as this as a "box frame" arrangement, giving lateral stability to the building and also spreading the load back along the existing foundation.

If you did this, and avoided bearing onto the middle wall, you would probably need (at risk of upsetting GRRRRaint ) a 254 UC beam (possibly 305 UC) and 254 UC columns.

So you would have an outstand at the walls of around 300mm. Might be possible to push the beam up above the ceiling so you haven't got a downstand.

Otherwise, we might design a frame that went between one of the external walls and the middle wall, and have a separate beam the other side. Would be able to use smaller sections then.

Either way, we wouldn't do it without columns for stability.

*Edit* As your house is detached you will need columns or piers both sides. Might be possible to hide the columns in the cavity wall and build the wall out flush. With a beam spanning the whole length you have the option of removing the central wall too.

 

[theoldun]

Out of interest, where is soil and vent pipe?
oldun

 

[ADENCOOL]

The sv is in the corner between the two room, on the above plan it's represented as a small box