How can you minimize fasteners?

Originally Posted by AaronB.

Also, studies have shown that with screws and plates running all the way through the insulation assembly and exposed to the final roofing membrane, that depending on the climate, you can lose up to 80% of your thermal efficiencies via thermal bridging through the fasteners.

Always better to fasten the bottom layer, and adhere or spray the top layer(s). This GREATLY reduces the themal bridge effect, saving the customer buku bucks over the life of the roof, all things considered.

Originally Posted by Tatnic

Being an engineer, I tend to fret over some things that others may not care about. For instance, I don't like the idea of using so damn many fasteners for a flat roof project. You're screwing down the lower layer of tapered insulation, then the upper layer, then you're screwing down the membrane. You've got a lower layer of insulation (and roof deck) with way too many penetrations. Isn't there another way to do this without so many fasteners? Again, I've never done roof work but here's what I'd do if it were my roof (please let me know where I'm going wrong here):

First of all, I'd rather have the insulation in one layer, even if it is tapered. But if that's not possible, then I'd section off the roof in segments that could be done in one day or less. I'd spot glue the insulation to the deck, spot glue the upper layer to the lower layer and then immediately place the membrane and mechanically attach it. That way I have only one set of fasteners and not 3. Alot less thermal bridging and damage to the deck. I'd also try to hit the 2x8's that are 16" o/c., but that's not going to be simple. Am I worried about nothing here?

thanks in advance.

Originally Posted by Tatnic

Here's what we ended up with: tapered iso, fully adhered, 2 layers, and fully adhered PVC (72 mil). It was about 15% more expensive than mech. attached, but given that the existing roof deck had no penetrations (except into the roof joists) I didn't want to add any new ones.

There was an Irishman on the project (on loan for a couple of weeks) and he says they can't use fully adhered in Ireland...its too damn wet. If we had tried to do this job in June we would of had the same problem.

Originally Posted by Grumpy

Now get the customer to pay for the adhesive which is at least twice the cost of screws and plates.

Originally Posted by Scott Holloway

Just curious, How old was the roof you replaced and was BUR or asphalt ever considered?

Thanks
Scott

Originally Posted by Tatnic

The total cost, including tear off, was around $120/square.