Hi all,
I am building a sunroom/garage extension on the house and have a couple of questions for those of you have done this before.
Is it ok to double up the DPM (1200 gauge 300ubore)? just to be sure as we are on moderatly damp soil and I want to be really sure I don't perforate it (it is on a 1 inch sand blinding). Couldn't get 2000 gauge.
I want to lay the Kingspan insulation and do some plumbing (for rads etc)
- How do you stop the whole thing from filling with rain water? does it matter? I know the cement slab is going to be damp, but the kingspan boasts non-permeability - is the water just going to sit there? (don't tell me to use a pitch fork to create some drainage holes in the DPM!)
I was talked into of 3 inch kingspan (TF70 - urethane) for the sunroom - I was thinking of 4 inch but the guy in the BM said I was nuts! £36 per 8x4 sheet (need 40sq.mt - rads, ext wall of glass) Am I nuts? (keep answers related to this particular issue!)
Finally - Is it really necessary to have a screed over the slab? I am going to use readymix, so a little bit extra would save a lot of mixing for a 2 inch screed (65sq.mt area). I would take my time on a good finish and if the worst happened I could use a levelling compound? The sunroom will be finished with wood and the garage will be painted.
Thanks for any advice - hopefully further questions will be related to the roof!
Thanks,
Derek.