I’d like to take you through the correct preparation of an old roof, through to how we insulates it and cover it with an EPDM rubber membrane. This is a standard procedure for commercial flat roofing.
First it is necessary to strip the old covering that was green mineral felt covering and you can see we have exposed all the old decking. We will do a small amount of repairs to the old decking – actually its in quite good condition especially because we are going over it with insulation we will be covering the decking with boards.
Its slight unevenness is not a problem. You can see here we are removing the old roofing system In the background I’m there filling in the old skylight area so no rubbish falls down there. The windows are open because we are going to take them out and the new roof and insulation will be higher and the windows will be replaced.
On this project on a commercial building in Winston Salem you can see that behind the windows we have dust sheets because this is going to be a warm roof the insulation is going to be on top of the old roof decking and we will insulate behind the gutter board. To do this we have to remove the old guttering and gutter board thus exposing the gap we clean between and fill with roof insulation. Insulation goes between the top of the wall to bottom of the decking continuing the insulation properties all the way around the roof. We have to work quickly so we can get the roof covered before the end of the day.
In the next part of the video you will see me working on the skylight, the others are laying the vapor barrier from other end of the roof. We are using a high quality vapor barrier, this is generally called a vapor control system – It controls vapor that transfers thought it into the insulation.
This particular vapor control system is strong and will span gaps of over 125mm. The roof decking is not good but the vapor barrier will bridge problems. Note the detailing of the vapor control system – It goes up and around the skylight, it goes up the walls and by the time this vapor control is down this roof will be waterproof.
Now we fix down the roof insulation using thermally broken fixings, again the roof insulation is fitted tight around the skylight around the walls and any gaps are filled using foam. The curb for the skylight goes over the insulation, making sure there is no chance of thermal bridging.
Gaps around the outside are filled with foam and the insulation is above the window cill where the old windows would have never opened while the insulation has been going down. We backfilled between joists, primed all joist ends, primed the fascia board that goes over the top and now the customer’s chosen to use timber because this is an old property
We could have used UPVC, however this looks better – in fact it looks very very nice now. This is just a step back a stage or two because we’re going to show you what we’ve actually done before when we put the facia back on. I’ve insulated behind the facia and I’m actually painting that later, once we’ve covered it with the vapor barrier which comes across the decking up and over-the-top, and with a piece of treated timber we will but the installation directly up against the roof.
Later we will fill between the joists below and as you can see I’m painting the gutter board that goes over the top of the insulation. The EPDM membrane has been down for quite some time and it’s been able to relax in the creases and we see the roof insulation fixings. The insulation is level, the vapor barrier comes up around and laps over the top so we are now ready to glue down the EPDM roof system.
Now the EPDM is down we carefully clean the roofing system – but very very slow so it’s very important for us to get it perfectly smooth. When all the lead flashings are on you can see the guttering looks good against the wood facial board and you can see where it holds back the insulation. Towards the back you can see the black UPVC termination strip and the extra height of the insulation makes this new flat roof around 125mm higher than the old roof.
So to finish let’s just have a look on the roof – I think the first thing that becomes apparent when you go onto a new EPDM roof especially when theres insulation under it are all the marks showing through this is part of the EPDM roofing system. We see all the joints between the insulation, the slight marks where the EPDM was packed for traveling and it has a slight ridge.
The EPDM rubber will shrink back a little but none of this is detrimental to the EPDM roof. If I apply pressure I can dent the surface, so don’t walk on it with sharp shoes
Thanks for watching my name is Eric Hunton from Winston Salem Flat Roofing. I hope this has helped you.