Double Garage Door Lintel / Beam?

[GarethB]

My builder has suggested using an appropriate UB on both the inner and outer course of blocks, and then boxing it in prior to rendering. There is a substantial gable over the garage (4.8m to ridge) however the roof is being built using attic trusses rather than purlins, so there will not be that much weight over the door. Both internal and external courses are concrete block.

I am not happy about the us of a UB, as I would like a row of vertical bricks over the door to tie in with the house.

Is it possible to use a Catnic type lintel? I've seen some listed, but them seem very expensive when compared to a UB.

Alternatively I've seen UBs with a metal plate welded to the bottom edge to take the outer course, but not sure whether this would be suitable for such a large gable.

Any ideas / suggestions would be appreciated.

Thanks.

 

[noseall]

From your description i gather the opening is directly beneath the gable?

If so, then the lack of natural 'arching' does mean either a heavy duty (expensive) catnic style lintel with say 250mm end-bearings or something like 150mm x150mm hollow box section with 6mm welded plate on the bottom to carry the outer course.

What does the designer say?

How wide is the garage door opening?

 

[RonnyRaygun]

You could use a UB or a PFC with a plate welded to the bottom. If there is a purlin then as you say it doesn't sound like it is particularly highly loaded. What is the span? Is it a single or a double garage?

Sorry, read your OP wrong...

 

[GarethB]

Thanks for the replies.

The opening is under the gable, and is a standard double, 4.27m (14 foot) opening, and the overall outer width is 5.5m. The door opening is 2.1m high, with the top of the ridge 2.7m above this (regular pitched roof, approx 45 degrees). Length is 7.5m.

I've put the question to the structural engineer, but as I said, the architect and the builder suggested using boxed in regular UBs, which I'm not happy with. They also reckoned on using a traditional roof contstruction until the structural engineer suggested using attic trusses which makes more sense to me.

I had a look at the Catnic lintels, and if my thoughts were right, it would cost in the region of £400.

Thanks again.

 

[RonnyRaygun]

So it's basically carrying a triangular load from the masonry and a tiny bit of roof?
What is the wall make up? Block inner / brick outer? Aggregate blocks? Lightweight blocks? Any rendering?

 

[GarethB]

So it's basically carrying a triangular load from the masonry and a tiny bit of roof?
What is the wall make up? Block inner / brick outer? Aggregate blocks? Lightweight blocks? Any rendering?

Exactly that. 100mm concrete blocks on both courses, with a render finish. There will also be a window in the gable, but I wouldn't have thought that it would affect anything.

 

[RonnyRaygun]

Ok, done a quick calc and you will struggle to get a Catnic lintel to work for that span. Extra heavy duty Catnics at 4.5m have a SWL of 32kN and I think your loads exceed that.

You should talk to your SE about it though as he might be able to shave a bit off the loads and spans (I'm being cautious).

Alternatively talk to him about a 180x90 PFC or a 203x133 UB with a bottom plate.

Hope this helps,

Craig.

 

[GarethB]

Alternatively talk to him about a 180x90 PFC or a 203x133 UB with a bottom plate.

Hope this helps,

Craig.

Thanks. Much appreciated.

All I need is for the SE to respond to my emails now...