Garage Conversion From 2 Single Doors to 1 Double Door

[rhino707]

Hi Guys,

I'm looking to get the two single doors in my double garage converted to a single door. I've read lots of posts in different places that discuss the need for an RSJ but a builder that I've had round, who has done a number of such conversions, reckons that an RSJ is not needed. He said that some other much cheaper piece of metalwork would span the gap as the steelwork is only supporting bricks above it that he would remove. He said the only externally visible part would be the loss of the single row of bricks visible above the the doors on the outside (in addition to losing the central pillar!). I'm not at all clued up on what he was talking about but does that make sense to anyone?

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[robbieee]

//www.diynot.com/forums/viewtopic.php?t=28095

 

[alan333]

It's difficult to tell by the pics which way your main rafters run (ie left to right, or front to rear), but it looks to me like the front wall is supporting the weight of at least the hip.

 

[Nige F]

Agreed , not a clear pic. But the trussed roof does run front/back and the hips are supported on the trusses that run to the centre of each door Did your builder actually look inside the garage

 

[rhino707]

Thanks for your replies.

The roof has the same pitch on all 4 sides with an apex in the middle, but the main rafters do run from front to back. I was fully expecting that an RSJ would be needed because of what I've read about others people's jobs, but as I'm fairly clueless on these matters I don't know what other options there are.

I take it from what you've seen, there is no other option, e.g. if all the bricks currently supported by the metalwork were removed and the central pillar was removed, is there anything, other than an RSJ, that would span the 5 metre gap to support roof?

I know that every installation is different, but does anyone have a ballpark figure for how much a typical RSJ would cost in this type of install (just for the RSJ itself)?

 

[arbitrary]

I'm interested in doing much the same - converting two single doors to a double door. The garage was built in the late 80s and is single skin brick construction with a trussed roof with the trusses running front to back. There's a one-piece wooden beam in place (4" by 8") running across the front of the garage supported in the centre by a pier of bricks. I have had two quotes for removing the pier - both want to replace the wooden beam with a steel. One builder has listed the steel as 302x127 and the other hasn't (yet) provided the dimensions. Either way the steel will be about 4.6 metres in length. The quotes have both come in around £2400+VAT. That's without a new door.

I'm astonished at this cost - it seems well too high. Neither quote is itemised. Both builders come recommended from previous customers and neither gives the impression of taking the proverbial but £2400? Or do I have an unrealistic expectation?

 

[noseall]

Whoever said that those garage door lintels are only supporting masonry is either a blind, a knob or ain't no builder.

Not only are the lintels supporting a few common trusses they are also supporting the girder trusses which in turn are supporting the entire hip ends.

Honestly!

 

[rhino707]

Whoever said that those garage door lintels are only supporting masonry is either a blind, a knob or ain't no builder.

Not only are the lintels supporting a few common trusses they are also supporting the girder trusses which in turn are supporting the entire hip ends.

Honestly!

It was me that was the knob, misunderstood what the builder was saying. Eventually got the job done. Builders charged £900 to remove old doors, central pillar and old lintels and to install new 5m wide RSJ. It was then £1700 for the supply and fit of the motorised door and control panel. All prices include VAT.

The job was easily completed within the same day.

 

[arbitrary]

Just had this completed as well - replaced a 5.1m 100x200mm wood beam, central pier/pillar and two single up and over doors with an RSJ and full width roller shutter door. RSJ spec was calculated by an SE as needing to be 203x203x60 sitting on padstones. Might be over-specified but should hold the roof up!

 

[bernardgreen]

He said that some other much cheaper piece of metalwork would span the gap as the steelwork is only supporting bricks above it that he would remove.

Get a new builder. The roof is resting on those bricks. So therefore the steel work is supporting the roof as well as those bricks.

Employ a structural engineer and ignore that builders opinion

That brick column is the size it is to provide adequate support and stability for the roof. Remove that column and you may then need to add extra supports at the side walls to take the weigh of the roof and the essential RSJ


OOOoopps I should read the last post before commenting

 

[Deltamale]

An IG or Catnic box lintels could have been used but they are only available up to 4.8, to short for your application as you need an additional 300mm to give the minimum 150mm bearing each end.

There are some lintels over that length, intended for extreme load cavity walls but they are very expensive.

What you need to consider is the cost of these light weight lintels, especially once you go over the standard lengths.

Certainly a UB will be much cheaper and can be obtained in just about what ever length you need.