Advice on Garage Build

Fantom

Fantom

Fantom

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Joined
13 Feb 2006
Posts
2,445
Location
Cornwall
Hi,

Im looking at building a new garage and have put together some quick plans, those eagle eyed among you will spot discrepancies between the elevations and the cross section but I am mid edit...

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What are your thoughts? Im a little unsure on how to create the roof as cheaply as possible - any input would be much appreciated!
 
You've drawn cavity brickwork, is it a heated garage? if not you don't need a cavity, you could build 1/2b walls with piers.

What's with the funny roof pitch? do you need it that way, flat roof and 3 layer felt would be cheapest.

What's the context, garage in middle of field or industrial estate of next to house?
 
Thanks for the reply Macca, im building cavity walls as they need to act as retaining walls on the side and rear. I dont particularly need the roof pitched like that but I like the idea of headroom, I have a 2m pillar in place at the moment as im not sure about the allowable spans.

The garage is going at the back of my garden with a long driveway leading up to it.
 
Your joists will be massive at that span, you may need one steel 'I' beam down the middle then you can split the spans to something more manageable and loose the pier, I'd stick it at your ridge then span down to the wall plates, covering you can choose a nice slate to the front but I'd expect the rear to be too shallow for a tile so a 3 layer felt or a single ply roof will do.
 
Do you want face brickwork, I'd build it it in 140mm dense concrete blocks with the steel on a pad stone the get it rendered or boarded with shiplap
 
A cavity brick wall will be no good as a retaining wall.
That will need to be made of hollow blocks and filled with concrete (ideally with re-bar down the cavity also)

Roof either needs to be a standardised pitch (cheaper trusses) OR as Macca says, flat roof the thing with just straight timbers and felt
 
Yeah, the I beam might be the best way, it may be silly but how would I attach the rafters (not sure if thats the correct term) to the I beam?

I had thought slate would be nice on the front and as the rear isnt seen some plastic coated steel sheeting should do the trick.

Any idea how much an I beam would cost at that sort of span?
 
Scubascorpion said:
A cavity brick wall will be no good as a retaining wall.
That will need to be made of hollow blocks and filled with concrete (ideally with re-bar down the cavity also)

Roof either needs to be a standardised pitch (cheaper trusses) OR as Macca says, flat roof the thing with just straight timbers and felt
Click to expand...

Hi, its not much of a retaining wall to be honest, maybe a couple feet of soil but it was also planned to keep it warmer in winter and to be generally more substantial.

I was hoping not to need trusses, would using an ibeam negate the need?
 
Fantom said:
Yeah, the I beam might be the best way, it may be silly but how would I attach the rafters (not sure if thats the correct term) to the I beam?

I had thought slate would be nice on the front and as the rear isnt seen some plastic coated steel sheeting should do the trick.

Any idea how much an I beam would cost at that sort of span?
Click to expand...

Timbers go between the I bean in the web of the steel usually on a timber plate that is fixed to the beam.

Steels is about £1,000 - £2,000 a ton depending on location / fixing etc etc
 
Cost of Ibeam isn't just dependant on length, you'll need it structurally "proofed" by engineer so that it can take a design weight (depends on choice of roof coating, felt being light, slate being heavy etc) also will need snow loading calcs which depend on pitch of roof.

Once that is done the engineer will give you the size of ibeam required over your desired length. THEN it can be costed.
 
Fantom said:
Hi, its not much of a retaining wall to be honest, maybe a couple feet of soil but it was also planned to keep it warmer in winter and to be generally more substantial.

I was hoping not to need trusses, would using an ibeam negate the need?
Click to expand...

Still wouldn't trust simple brick and mortar to hold back an earth wall.
It'll also be cheaper in block. Do up to ground level in block, back fill with concrete then continue on up with brick.
 
ok, thanks for that, am I right in thinking then that a flat roof would probably need a stronger ibeam?

How would you change the design if you were building it?
 
Scubascorpion said:
Still wouldn't trust simple brick and mortar to hold back an earth wall.
It'll also be cheaper in block. Do up to ground level in block, back fill with concrete then continue on up with brick.
Click to expand...

Sorry I forgot to say its going to be entirely 4" block with probably Tyrolean finish.
 
Fantom said:
ok, thanks for that, am I right in thinking then that a flat roof would probably need a stronger ibeam?

How would you change the design if you were building it?
Click to expand...

No a steel beam would be fine for both, not a lot in it if anything, if you looking at using the walls for retaining and using a beam in the middle you really should get a structural engineer to do some calcs and a drawing for you, should cost £250 - 400 depending on where you are.

Yes a pitch in there will be fine if the ends are strapped to the wall plate

I'm a surveyor I'd build a square box with a flat roof and have done with it but in the real world it all depends on context, where it is, who will see it, what's it being used for etc

Even at £500 a sq m a 7 x 7 garage is £24,500

Don't think it's unreasonable to expect £500 sqm, I'd build it for £10k though
 
A flat roof will obviously be much cheaper but a pitched roof has the advantage of providing storage space. I'm very lucky to have a double garage with a picthed roof large enough to climb up on a ladder and stand in the loft space. I now use it to store all sorts of stuff and it keeps the house nice and clear.

You might also want to consider feeding power to the garage too.
 
this is sounding like it's next to your house so if you want to have it "in keeping" with the rest of the buildings I guess trusses are the way forward. If you like the idea of headroom, have a look at raised scissor and scissor tie truss designs. Doesn't give you any usable roof space but gives you extended head room.

If you can build up the gable walls to to pitch height in block or engineered brick then you could use an I beam as your top rafter, then just drop the hips down to to eaves.
World is your oyster. :D
 
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maccapacca said:
No a steel beam would be fine for both, not a lot in it if anything, if you looking at using the walls for retaining and using a beam in the middle you really should get a structural engineer to do some calcs and a drawing for you, should cost £250 - 400 depending on where you are.

Yes a pitch in there will be fine if the ends are strapped to the wall plate

I'm a surveyor I'd build a square box with a flat roof and have done with it but in the real world it all depends on context, where it is, who will see it, what's it being used for etc

Even at £500 a sq m a 7 x 7 garage is £24,500

Don't think it's unreasonable to expect £500 sqm, I'd build it for £10k though
Click to expand...

Ok thanks, thats something to think about, I'm now wondering what sort of pillars I would need to put in to allow use of reasonable sized timbers to keep costs down...

I'm going to be doing all the work myself and will be on a massively tight budget, so tight in fact that I haven't even planned one! :o

The context is pretty generic, aesthetics don't matter what it looks like, used for general car works and diy etc.

Im hoping to speak to a roofer on Friday to see what he suggests.
 
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