Proper tarp size.

[gazza_11]

I need to tarp the 5.245m x 3.05m flat roof of my detached garage but I'm not sure if I should buy a 6m x 5m tarp, https://www.diy.com/departments/gro...green-tarpaulin-5m-x-6m-/5051641516196_BQ.prd, giving two 0.3775m and two 0.975m overhangs, or buy a 8m x 4m one, https://www.diy.com/departments/gro...green-tarpaulin-4m-x-8m-/5051641516202_BQ.prd, giving two 1.3775m and two 0.475m overhangs. Based on one particular website, my ideal tarp would be 6.465m x 4.27m, giving four 0.61m overhangs. The overhangs are to be wound round 89mm x 38mm battens which will then be screwed to the garage bargeboards. In general, what is the recommended overhang for tarping a flat roof of a detached garage, and, therefore, which of the tarp sizes should I buy, and would it be okay for me to cut either of those 'GroundMaster 250gsm Brown/Green' tarps to a different size?

 

[Wayners]

Temporary roof cover?

 

[foxhole]

I need to tarp the 5.245m x 3.05m flat roof of my detached garage but I'm not sure if I should buy a 6m x 5m tarp, https://www.diy.com/departments/gro...green-tarpaulin-5m-x-6m-/5051641516196_BQ.prd, giving two 0.3775m and two 0.975m overhangs, or buy a 8m x 4m one, https://www.diy.com/departments/gro...green-tarpaulin-4m-x-8m-/5051641516202_BQ.prd, giving two 1.3775m and two 0.475m overhangs. Based on one particular website, my ideal tarp would be 6.465m x 4.27m, giving four 0.61m overhangs. The overhangs are to be wound round 89mm x 38mm battens which will then be screwed to the garage bargeboards. In general, what is the recommended overhang for tarping a flat roof of a detached garage, and, therefore, which of the tarp sizes should I buy, and would it be okay for me to cut either of those 'GroundMaster 250gsm Brown/Green' tarps to a different size?View attachment 338956

No recommended overhang as it’s not something that is recommended . Fix the roof?

 

[gazza_11]

Just to clarify: the length and width of the tarp needs to be in excess of the length and width of the garage roof so that the edges of those excesses of tarp, overhanging the roof, can be screwed to battens before being wound round them, the battens then to be screwed to the fascia boards to firmly secure the tarp.

Yes; the roof needs (partially) replacing. I've already removed the bitumen felt and all but one of the fascia board edgings. I intend to remove the decking planks, install three purlins longitudinally on top of the thus-exposed joists if the joists are sound, which I've been advised by a professional they seem to be, otherwise replace them and might as well, in that case, remove the rest of the woodwork (firring strip; fascia boards; door posts); windows also need replacing. To the purlins I intend to install transparent—to let plenty of light in (despite, further into the future, possibly installing OSB boards to the undersides of the joists to create a ceiling)—corrugated roofing sheets and associated weatherproofing.