Roofing

Guidance on cabin wall build for flat roof with 1deg slope

Anonymous user 03/03/2024 - 3.32 PM

I'm building a 6m x 4m garden cabin with a flat roof. I'm planning the roof and walls and I'm trying to work out the option I want to go with to get the roof sloping from the front at the highest point to the back with the lowest. I've worked out I need an angle of 1° (1:60 or 0.2 in 12) based on my joist span which will mean the roof is 7cm higher at the front going down to 0 at the back. NB. I'm having a warm roof so insulation/OSB etc will be on top of the joists. I don't want to build rake walls for the side walls so my options as I see it are: 1. Have all walls the same height and use furring strips on top of each joist (there are 16) which will be just over 4m in length for slight overhangs). This will be quite expensite but will give me a level ceiling inside etc. 2. Have all walls the same height again but use 2 furring strips to sit beneath the outer side wall joists (kind of like packers to give the slope). Then add a length of 4" x 3" on top of the front wall plate to give me the approximate 7cm additional height. This will be cheaper but will give me a very slight sloping ceiling inside (I will have spot lights but I'm not too fussed about the slope). 3. Have all walls the same height except the front wall. This will be shorter so I can add some timber on it's edge to give me the 7cm extra height at the front. Then use 4x2 lengths sat on support blocks at an angle on the side walls to give me the slope. Like this (this cabin is 8m x 2.8m): https://www.alidymock.com/wp-content/uploads/2019/01/Photo-03-1.jpeg I'm leaning towards options 2 or 3 but wondered if it's ok to use furring beneath joists and whether there were any pitfalls generally into these approaches or if anybody had any other ideas on easy ways to do this.