Hi, I'm planning to replace an old flat roof and windows on a small extension at the rear of my house. I've had conflicting "advice" on one aspect, which lintels to use.
The extension is double skin thermalite blocks with an insulated 50 mm cavity. Wall A is completely blocks. Wall B will have 1 m high block work with a large aluminium window (1750 W x 1250 H) on top Wall C will have 25cm pillars either side with central aluminum bifold doors ( 2500 W x 2200 H) Wall D is the old external wall of my house.
The roof will be a flat roof (unsure on warm or cold insulation, that's another topic) it will have a parapet wall all the way round of 1 course of 9" thermalite blocks capped with stones.
My question is What lintels can / should i use above the window and bifold doors. Concrete or Steel Cavity Lintel?
Also on another note, with the works above do i need to notify the council to "replace" this existing roof. Its slightly different as the current one doesn't have the parapet wall. One builder said i didnt have to another said i did.
There's a company called IG LINTELS that supply long pressed steel lintels to suit just about any wall thickness. As long as you have 150mm bearing on each end and it's only a single storey building, their product guide ( I found it online.)will point you in the right direction. Buildbase and Travis Perkins usually have them in stock upto 3metres long. These lintels also provide a good base for a cavity tray above the doors/windows. I used a 3.6m long lintel above aluminium bifold doors without any problems.
Ref: notifying building control, If you're forming new window and door openings in a dwelling there are restrictions on the amount of glazing area, not sure of exact figure. And if you go for a cold flat roof they'll want provision for 'cross ventilation' if it's the roof of an extension.
DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!