EPDM Flat roof slope(s)

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ukmoley

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Hi. Please be patient with me as this is my first big build! I'm an Engineer by trade though so reasonably confident once I understand the basics.

I'm planning a large garden workshop and would like to flat roof it with Classicbond EPDM. The actual structure will be 6x4m in Thermalite blocks but I want to have a 2.5m overhang round two sides to create a covered wraparound deck area. Which gives me an issue.

As far as I know I can't get firring strips more than 4.8m long, so I'm thinking of having having a 'flat pent' with the firring running away from a central ridge.

Is this a standard method of construction for a flat roof and do I need run anything down the apex? I'm struggling to find any info on different slope configurations.

I'm quite limited on height by an existing thick concrete base and I'm only 1m from a boundary so I need to stay under 2.5m total height.

Thanks for any advice!
 
A flat pent?

Do you mean a flat roof which slopes in two directions from the centre? If so there would be no special treatment at the "ridge" but check with the EPDM supplier to see if there is a need for a relief strip/underlay at the ridge joint.

If you are not applying for planning permission, are you aware of the permitted development size criteria? The roof projections may contravene permitted development.
 
You can get firring strips as long as you want, they will just be in 2 parts that’s all. Give your exact requirements to a proper timber merchants and they will cut them for you.
 
Rather than mess about with deep furrings, its easier to angle the joists and then level the ceiling with timbers instead.
 
ukmoley said:
Hi. Please be patient with me as this is my first big build! I'm an Engineer by trade though so reasonably confident once I understand the basics.

I'm planning a large garden workshop and would like to flat roof it with Classicbond EPDM. The actual structure will be 6x4m in Thermalite blocks but I want to have a 2.5m overhang round two sides to create a covered wraparound deck area. Which gives me an issue.

As far as I know I can't get firring strips more than 4.8m long, so I'm thinking of having having a 'flat pent' with the firring running away from a central ridge.

Is this a standard method of construction for a flat roof and do I need run anything down the apex? I'm struggling to find any info on different slope configurations.

I'm quite limited on height by an existing thick concrete base and I'm only 1m from a boundary so I need to stay under 2.5m total height.

Thanks for any advice!
Click to expand...
You can go to 4m total height. 2.5m at eaves .
 
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