Workshop roof advice

[diviy]

His I have a 12x8 single block breeze block she'll built but the guy who was building it for me has tucked me up..All he has done is built a single block she'll and it is all the same height finally got a door and some windows to go in but I need a roof that is going to be a flat style roof. I have sourced the roofing sheets and timber but how do i create a slope for water run off the easier the better as I am going to have to get my wife and daughters to help due to.my back condition .

Any advice or links would be great
Regards Gerry

 

[novocaine]

frame it and fit facia.
4x2 batten secured to the top of the block work.
6x2 beams, 600 centres, you'll need 8.
first beams rests on top of batten. (toenailed or cross screwed to the batten)
second gets notched to sit lower, you'll need to work your slope out, 1-24 would be an inch out of each beam, this might not be steep enough depending on what you are using as sheeting.
third gets another notch etc.
once you are about halfway in to the beam (so around 4 beams) use joist hangers for added support.
stringers between beams to stop them racking.
fit your roof sheeting, how is depending on the skin, if it's ply then screw it, if it's corrugated use the right screws.
cut facias to go round edge and across front and back, exterior grade ply is best. I like cutting an overlap between joins so it can be sealed.

this does assume that the top of the block work is well above head height as the last beam will be below the top.

 

[novocaine]

someone will be along shortly to tell me I'm wrong.

 

[RobinBHM]

Your brickie has done it correctly really it wouldnt be worth cutting blocks for a very shallow fall.

As Novocaine says its best to start with fixing a timber plate around the top of the blockwork.

You can notch out each joist or you can double up the timber plate on one wall and lay all your joists across.

if you want an overhang then make the joists longer to suit.

If you want insulation then you can cut this in between the rafters directly below the top decking (assuming a flat roof not corrugated sheeting).

 

[whiskywill]

What about using firring pieces on top of level joists? Readily available from Jewsons and others.

 

[diviy]

Cheers guys anyone have a link to a image by any chance ? The place that I am getting the sheets from said 24 between centers due to there rigidity confused now lol.

 

[novocaine]

24" is 600mm.

no pictures, mainly because the roof on my garage is so bad I'm thinking of ripping it out completely and making a new one. I'm always amazed at what people are willing to bodge.

If I get chance I'll CAD you something up tonight, but I can't promise anything as I'm meant to be building a cupboard (amongst other things)

 

[diviy]

24" is 600mm.

They dont call me diviy for nothing

the other problem is that the rear wall is 6" is from a 18ft wall it was supposed to be a metre from the wall ! I was in hospital having spinal operations when he built it by the time I returned from hospital it was to late as it was built 3/4 of the way up .
So fitting the rear facie is going to be a problem .

 

[novocaine]

do it before you sheet the roof and screw it from the inside.

 

[whiskywill]

Cheers guys anyone have a link to a image by any chance ? The place that I am getting the sheets from said 24 between centers due to there rigidity confused now lol.

This is a "warm" flat roof with firrings. If you want the slope to go the other way fit the firrings across, instead of along, the joists. Can be done this way with or without the insulation sheets.

 

[Alexam]

This site may help https://www.youtube.com/watch?v=rdD1v7Ozpes

 

[diviy]

Timber coming Monday what fixing would you use to secure the wall plate
Cheers verry

 

[novocaine]

on the top of the wall? if so I'd be using rawlplugs and screws, it isn't under any real stress.

 

[diviy]

Finally got home tonight from our road trip in the camper and measured shed the actual size is 11 foot wide and just under 8 foot deep here is a rough pic of the layout


Can I use 4x2 as roof supports with plenty of support Noggins I am also looking to use osb board for the roof what thickness osb should I use?
The reason I would like to use 4x2 is due to the weight as due to my back injury with help from my wife and daughter the will be a more manageable size to work with .I am also going to use firring pieces on top of level joists to give me the run off slop. The door and windows are double glassed units out of of a skip.


Any other advice would be appreciated

Regards Gerry

 

[Woodchips2]

Hi Gerry
Rule of thumb for roof joists is span divided by 2 so for 8ft span 4x2" should be fine.

For floor joists it's span over 2 plus 2" so you'd need 6x2" for an 8ft span.
Regards Keith

 

[devonwoody]

I'm up the creek as well, I was suppose to be having fabricated corrugated metal roof fitted in about 14 days time but my roofer is attempting to install on a rotten 8x2 beam which is around 5.5mtrs long which is part of the lintel across a double garage. He knew it was rotten and needed fixing so a big row is coming up.

(I have spent around 4 days storing tools which must have weather protection so far and dont know where i stand at the moment) Looks like I am going to have to refuse delivery of the roofing sheets.

Anyone here in S.Devon interested in a big job?

 

[diviy]

Cheers everyone for the advice had a good look today the shed build is going on hold at present as the garden is so overgrown .
I have a hydrangea that is on steroids over 6ft tall and covering patio area that is access to new shed and blocking the front of my other shed and honeysuckle the other side also covering the patio.
I am getting a petrol strimmer tomorrow as the lawn is totally covered in brambles and ivy plus a load of other weed`s so no room to swing a cat but this will cleared for a deck and a work area to do the shed build . I am going to do a seperate thread on the build of reclaiming my garden and workshop/shed out of interest when does a shed become a workshop :? :? :? :?
To give you a idea how overgrown it is I have a cement mixer that you cant see due to the weeds before I broke my back the garden was stunning the lawn was like a bowling green HONEST