Waterproofing and insulation help...

[Jameseric]

My property has an old barn. When I purchased it, the barn was falling down. To save it I installed a metal roof and LP smartside to protect the timber framing. I installed the metal directly over the purlins. Now, I want to finish about 700sf of the barn for dry storage and an exercise room. As time goes on I know the metal screws will start to leak as the metal expands and contracts.

Before I remove the metal roof and install sheathing and roofing paper under the metal. I'd like to be sure I don't have another option.

Is there a way to waterproof under the purlins to ensure that the insulation does not get wet?

I can use anything but this what I have on hand at the moment:

- (40) sheets of 2" rigid foam board
- tons of pressure treated lumber
- Water and Ice Shield

Thanks in adavance for your input.

 

[csp]

Did your screws have the rubber gaskets? If not, swap them out for the right screws.

 

[e-tek]

csp hit the rubber screw on the head so to speak. If you can't seal out the moisture from the top side, anything those screws pierce is going to get moist. Best practice is to try and hit solid wood with roofing screws.nails, but it rarely happens. Reason roofing nials stay dry is the next layer of shingle is always keeping those last nails dry. Your screws are out in the open, hence need to be sealed with those rubbers. If you're removing and redoing, get the right screws but also put stripping thick enough that the screws don't penetrate it.
I've had to do this with several outbuildings at out farm/cottage.

 

[csp]

Just for reference, my building is 30 years old and doesn't leak a drop around the screw holes.

Here's the right kind of screw to use. The gaskets are actually neoprene I believe. I've seen them in the big box stores like Lowes and Home Depot.

 

[5lima30]

Also its best to have non-pressure treated lumber for purlins. The pressure treatment causes the screws to corrode just below the metal roofing.

 

[dirttracker18]

Yup, had to do this on my house went I bought it. The guy had nailed the roof down. I had to pull all the nails and put screws in. What a hellava job trying to pull all the nails without damaging the roof.

 

[Jameseric]

Those are the screws I have installed in white 2x4 lumber. I just assumed they would leak one day down the road. But if they are okay, I guess I don't have a problem.

 

[OldtruckDude]

Just for reference, my building is 30 years old and doesn't leak a drop around the screw holes.

Here's the right kind of screw to use. The gaskets are actually neoprene I believe. I've seen them in the big box stores like Lowes and Home Depot.

X2............If you have some places you miss with the screw, you can get a roofing product similiar to tube silicone in order to seal it up. If the metal roof is done correct, it will last your lifetime.

 

[Daniel Dudley]

I have had a lot of guys tell me how they are ''going'' to leak, but I have never seen one leak. in the old days before the screws, they had ring nails wrapped with a lead cap.

Now those will leak eventually.