heightening roof beams in a garage?

[Berwyn32]

Hi, I'm new to this forum & hope I have posted in the correct place.

I have a large 12m X 4.40m garage, in fact it is 2x garages joined together, of wooden construction 2"x3" beams covered with wooden cladding, one half roofed with corrugated tin, the other fibre type corrugated.
I am at present dividing them back into 2 separate sheds, replacing the central wall, to use one half as a workshop/office for my computer business. This will be rewired, insulated, lined with plaster board & a ceiling installed.
I want to raise the 2”x3” trusses, which run across the width of the building to about 20cm from the walls at each end, to increase the ceiling height. If I raise these up to the next beam up on the roof, I will gain 28cm, which is adequate for the purpose of the job.
When divided the workshop area will be 5.5metres in length, 4.4 metres wide, with a ceiling height of 2.18metres high. There are 3 trusses which need to be heightened. Is this possible, or is there a set out calculation which limits this?
I can supply pictures & further information if required.
Regards
Dave.

 

[ladylola]

Yes pictures would be a great help.
By the way if you are removing the dividing wall (I'm assumming the garages are side by side) what will be holding up the truss ends?

 

[Berwyn32]

Hi,
No, sorry if my description was a bit vague? The garages are joined end to end which is why it is such a length, both garages are 4.4 metres wide, the original garage had the end removed & a second garage joined to it, I bought it like this, I am going to build a dividing partition wall where the back wall of the garage would have originally been. This is the front view of the workshop, windows will be removed & replaced with a central door with a window either side.
View media item 38449I want to raise the height of the cross members up to the beam shown. this will give a ceiling height of 2.18M.
View media item 38452 View media item 38453
there are 3 cross members to raise
View media item 38450The beams do not actually span from wall to wall. Am I correct in thinking that as long as they are fitted below the first beam, that it will not have any great impact on the current strength of the roof?
View media item 38454Please excuse the mess, being used as a dumping ground at present View media item 38459

 

[ladylola]

Yes now I understand , perhaps I should read posts more carefully
You should be ok doing what you suggest. To do it first put in place the new collar at the higher point before removing the exsisting collar. I'd bolt rather than screw or nail the connections as well.
Tying the new dividing wall to the roof will also help counter the forces trying to push the rafter bottoms apart too.

 

[Berwyn32]

Thanks for that,

I was going to go to the trouble of acro props, removing the existing woodwork then replacing it, But bolting the new beam onto all the existing woodwork & cutting away everything below it will save a lot of time.

Thanks again,

Regards
Dave

 

[Berwyn32]

Hi all & a happy new year, although it's been a while since I posted this question, I would like to thank ladylola for advise given.
I have completed the job & now have roof beams some 18" higher, the roof is just as strong & had 4-5 " of snow resting on it for several days without a problem, I am now going to paint the asbestos sheets with Wickes acrylic roof paint to ensure weather resistance.

I now need to replace some of the tongue & groove boarding around the sides of the building & two of the wooden beams running along the base of the shed are rotten. These timbers support the whole shed & I intend to replace with new timbers bolted to the floor on top of waterproof membrane, then seal the outside bottom edge with a sealant before fixing new wooden cladding.

Does anyone know of a better method of ensuring water does not enter the shed under this timber?

Thanks in advance.
Dave

 

[ladylola]

You could always replace the bottom timber fixing it higher than it sits now and put a course of bricks and dpm down for it to sit on. That way your timber and of course the ends of the t&g boarding will be above ground level and away from any water lying there.I'm assuming the garage is sitting on some sort of concrete base so fixing can be done afterwards by steel straps screwed to the studs and with a 90* bend on the bottom fixed to the concrete.
You could of course do this by simply raising the whole garage if you wish.