workshop roof.

[Joe Shmoe]

Hi folks, thinking of building a new workshop and currently making plans and doing sums.

Wondering if I should make it a flat roof this time, as I feel it would be easier, quicker and cheaper. Thinking of doing something simular to Shultzys awesome build here, but have a couple of questions for him, or anyone else who might be interted in sharing view.

shultzy-s-shed-workshop-build-really-lots-of-pics-t17187.html?hilit=flat%20roof&start=30

1) Was thinking of using a one-peice EPDM membrane instead of felt, but cant work out how to finish the underside ? I cant tell from Shultzys photos what he did? Is it okay to leave the OSB roof sheets exposed on the underside? Wouldn't that look unfinished, but cant workout how I could cover them instead ?

2) Im sure there is a good reason, but why did he build the roof trusses that way he did, instead of just making one wall slightly higher than the other, and stretching 2x8s accross ? Wouldn't that have given more headroom ?

Regards
Joe.

 

[Carlow52]

Re the roof trusses, I am surmising from his comments that he had a lot of the material to hand, as opposed to buying it.

The trusses are a much better job than some twisted, knarled, split, bowed, warped 2 by 8 :lol:
They also eliminate the need for noggins

Re the roof finish have you considered insulating it and if so how and how will it be ventilated?

 

[Shultzy]

1) Was thinking of using a one-piece EPDM membrane instead of felt, but cant work out how to finish the underside ? I cant tell from Shultzys photos what he did? Is it okay to leave the OSB roof sheets exposed on the underside? Wouldn't that look unfinished, but cant workout how I could cover them instead ?

2) I'm sure there is a good reason, but why did he build the roof trusses that way he did, instead of just making one wall slightly higher than the other, and stretching 2x8s across ? Wouldn't that have given more headroom ?

Regards
Joe.

Hi Joe, glad you liked the build.

Question one: I covered the trusses with polythene dpm and then put the ply on top. The felt is "Easyseal" underlay and capsheet from Wickes. It is self adhesive and is guaranteed for 20 years. The underside is lined with insulation and mdf (see photos near the bottom of page five)

Question two: I built the roof trusses for two reasons. I would only need one size of timber (4x2) so less waste, and I wanted somewhere to put the overhead electric points.

The trusses are over engineered so no problem with hanging anything from them (I have an air filter up there). If it was only one joist, calculations would have to be made to make sure it will carry the load as guessing 8x2 is not good enough (snow can be quite heavy).

If there is anything else you want to know, ask away

 

[OLD]

This info on my workshop build may be helpful any further info just ask.
https://www.ukworkshop.co.uk/forums/extending-my-existing-flat-roof-workshop-t23279.html

 

[Nicknoxx]

You may be interested in my shed build pictures:-
http://www.flickr.com/photos/28412774@N ... 522920528/

 

[Joe Shmoe]

Thanks for the tips and great pics.

Im still pondering over whether to go for pent roof (ala Shultzy) or an apex.... this has been made even harder as I managed to pick up 50 lengths of 4x2 for half-price, but they are only 3.6m long so have to work around that length as I dont want to buy any more timber.

Looks like I will be having 1800mm uprights for the walls, so I can get two cuts from each length - when you add in the single course of bricks, and the two top-plates, that makes it close to 2m - which is probably about right, I guess?


Anyway - here is a first mock-up of the design so far.

Im a bit unsure of two things.

1) How do I cut a long angle along the top of the bottom chord so both chords join at the right angle (which, btw is 6degrees - is that suitable?)

2) How do I finish the edges of the roof? I was planning on laying a one-peice EPDM across the whole thing but have never used one before. I guess I have to attach a fascia board to the end of the toip chord - the question is, does the OBS roofsheets overhang the fascia or are the chords and OSB cut flush so that the Fascia board covers both ? Good grief .... I've just read that sentence back and it makes no sense?!

 

[hunggaur]

Hi folks, thinking of building a new workshop and currently making plans and doing sums.

Wondering if I should make it a flat roof this time, as I feel it would be easier, quicker and cheaper. Thinking of doing something simular to Shultzys awesome build here, but have a couple of questions for him, or anyone else who might be interted in sharing view.

shultzy-s-shed-workshop-build-really-lots-of-pics-t17187.html?hilit=flat%20roof&start=30

1) Was thinking of using a one-peice EPDM membrane instead of felt, but cant work out how to finish the underside ? I cant tell from Shultzys photos what he did? Is it okay to leave the OSB roof sheets exposed on the underside? Wouldn't that look unfinished, but cant workout how I could cover them instead ?

2) Im sure there is a good reason, but why did he build the roof trusses that way he did, instead of just making one wall slightly higher than the other, and stretching 2x8s accross ? Wouldn't that have given more headroom ?

Regards
Joe.

built mine with the back wall larger than the front one, place 4 beams across the span then put 12mm ply on top, then a breathable membrane, then put on 2 by 2 beams 18 inches on center then clad the roof with 12 foot corrugated steel sheets. i was then able to insulate and then clade between the internal beams. very secure very weather proof and total cost around £150.00

 

[Digit]

Joe, I have used the rubber, (EPDM) and it is quick and easy.
If it a sloping roof with a gutter at the lower edge all you need is a triangulat fillet on the other three sides to stop water blowing off the edge.
If the roof overhangs, tuck the membrane on the underside or glue it into place using suitable impact adhesive.
If no over hang there are specialised finishings available.
I'm on a borrowed lap top at the moment wich is very slow, I've posted this but if you wish I'l try and locate on Google my suppliers and the tech info.

Roy.

 

[Shultzy]

Hi joe, the mock-up looks good and familiar :lol:

How do I cut a long angle along the top of the bottom chord so both chords join at the right angle (which, btw is 6degrees - is that suitable?)

I think mine was 7 degs but 6 should be ok, it's a reasonable fall. I made a jig and cut the angle with a circular saw.

I screwed the fascia board to the truss first (page 3, pic 4), then put the boards over the top. At the front I left a slight overhang and trimmed it off with the router. If you want to go the "whole hog" you could put a round-over all the way around, but its not really necessary.

I'm assuming you have left the noggins out to make the drawing less complicated, I put them on the drawing to make calculating the amount of timber needed easier.

 

[Joe Shmoe]

Its been a while but I am finally cracking on with the shed build. So here is a pic of progress so far..... I made a few changes before starting, and a few more while building (I know, reciepe for disaster). Basically, its 4x2 studwork on 2course of engineering bricks...... 2.9m x 2.8m

I have loads of 4x2 left which I would like to use to build the roof instead of buying more wood, but I am worried that 4x2s may not take the load in heavy snow.

If I continue with the Truss ideas mentioned previously (a'la shultzys design), do you think a 4x2 could safely span a 2.8m gap? (I would probabaly leave them as 3.6m lengths and have a 300-400mm overhang all around). I have knocked up a quick sketch-up, and placed them at 400mm centres. What do you think ? (I have left out noggings etc as it was just a quick knock-up). Also, I dont think I will be able to get away with anything more than a 7degree pitch if I am to stay within planning height

As for the final roof covering, I am still unsure whether to use a EPDM mebrane or Coroline sheets, or just a basic felt that you replace every 5 years etc. Its not seen from house, so the only deciding factor is which-ever will be leak and trouble-free for longest.

Any ideas on load capability and what I should cover it with ? Thanks for any advice guys.


joe.

 

[OLD]

From the tables for a flat roof dead load 0.75 to 1.0 kn/m sqd. for maintenance or repair access. good strength timber 50x147 at 450mm span is 2.97m.
50x97 at 400mm will span1.81m so a central support will be required sorry not able to do calcs for this .
Me i would go for 2x6 at 16 inch ctrs. for a solid job

 

[Digit]

Unless you're a teenager joe, or intend living forever go for the EPDM, it will outlast you.

Roy.

 

[Alex]

Good start Joe.For your roof I'd brace/web between rafter and ceiling joist to make truss construction. Two diagonal pieces between each to spread weight, bolted on with M12x125 coach bolts. Then fit 4x1 diagonal brace on under side of rafter from top right corner to bottom left.(stability brace.) Then just nog between ceiling rafters at wall plate and down the centre to stop twist. Also remember to leave cross flow ventilation above insulation.
+1 for edpm roof covering.
I used it on mine, somewhere on here is my shed build in projects area.
My method was to fit full sheet osb covering screwed down,chalk line then trimmed with circular saw. I routed a 1/4 round round all edges where the EDPM needs to ease over. Now unfold edpm onto roof an leave for couple days before glueing to get creases out, just fit few battens round outside where the barge board and gutter go so it don't blow away. On mine i glued all the way to edge, left 4" rubber over hang no fillets and used the plastic barge board they sell with foam on the underside to stop over spill. The gutter side I opted out of there gutter trim which screws to fascia board to secure rubber because it would push the gutter a further 3" down. So I glued right to edge with proper contact not water base on here and trapped over hang rubber in gutter with leaf guard. Anyway pic probably explains better.

edit-ignore what i say it's already been said. Good advice guys.
Shultzy all your pics are not showing in your posts.

 

[Digit]

My home was originally roofed with corrugated asbestos cement sheets and is now now, in part, recovered with EPDM and it really is as easy, and good looking, as Alex suggests.

Roy.

 

[Joe Shmoe]

thanks guys - valuable input and I am def convinced on the EPDM now. Thats what I am gonna go for.

I'm starting a new thread in the Projects section seeing as that would be more appropraite now that work has started!!

see you there.