What Lintel?

[Ydraiggoch]

Hi,

I'm going to be cutting in a new window for a room I'm renovating. From what I can gather, my intended method is not the 'standard way' you would do this job, but still an acceptable way to do it. Let me explain;

The wall is cavity wall, block construction. I intend to cut the outer wall slightly smaller than the size of the window (UPVC frame) so that the window will butt up against the inner side of the outer blockwork. (The inner wall will obviously be cut large enough for the window to slot into.) My reason for this is that every other window in the house is installed thia way, meaning there is a 100mm recess on the outside for each window. If I were to fix the window to the outer block work as I believe it would normally be done, the recess would only be approx 50mm. Plus the cill would look different too.

Anyway, my question is what Lintels should I be using for this job. The existing Windows all have an Angle iron beam (L shape) both on the inner and outer walls. As far as whats above the new window, by the time its cut out, there'll be about one course of Block work, then its the roof (so trusses sitting on top).

Should I look to use Steel Angle Iron or is it better to use a concrete lintel? I notice the Steel Angle Iron doesn't seem that commonly available as Concrete or Catnic type lintels and wondered if there was a reason for this.

Thanks in advance.

 

[tony1851]

Concrete lintels would be OK, depending on the span. If supporting roof trusses, a 140 x 100 pre-cast lintel would be a minimum.
Nothing wrong with using 100 x 100 angle for either skin, again depending on span.
Builders merchants tend not to stock hot-rolled sections - you would go to a steel stockholder for those.

 

[Leofric]

What is the span and could there be a point load from a girder truss on the lintel perhaps ? Who knows ?

 

[Ydraiggoch]

Hi Thanks for the replies,

The span of the Window will be 1750mm. Above this (from what I can make out, there are about 3 Roof Trusses that are sitting on the outer wall. So my plan will be to use Scaff Board & Acros to support these while I cut and fit the Lintel.

I'm assuming a 2000mm Lintel will be sufficient giving 125mm either side of the opening. Or should this be more?

I will call round some Steel Merchants to see if I can get something suitable.

Thanks again

 

[tony1851]

On that span, 100 x 100 angle might bend a bit, particularly if supporting trusses.
Something like a steel 'I' beam 127 x 76 would be more than adequate.

 

[Leofric]

Are you sure the roof trusses sit on the outer skin , not impossible , but they usually sit on a wallplate on the inner skin of an external wall.