Tag Archives: Emseal self-expanding closures

Don’t Let Valleys Get You Down

When it comes to post frame barndominiums, rooflines run from simple gabled roofs, to complex designs including hips, valleys, reverse gables, etc. Basically, if you can imagine it, post frame can provide a design solution.

Loyal reader (and my Facebook friend) RUSS in PIPERSVILLE writes:

“Hello Mike. As we get a little further along with our design I would like to ask for your opinion. I read in past blog topics that you don’t recommend designing roofs with valleys when going metal over purlins. Our current plan has a large reverse gable on the front of the house covering the entry and porch and our utility mechanical room is a reverse gable room attached at the rear. All roofs are 6/12 pitch. I’m a bit worried about getting the details right. Is it that difficult to install the metal roof correctly over purlins, or should I just consider installing solid sheathing with metal over? Perhaps forego the metal and return to wood deck and shingles? Tom Z. has been a help in explaining how the gables must be framed but I must confess that the details don’t leave me all warm and fuzzy about the roof construction. Any insight you can offer is always appreciated.”

Mike the Pole Barn Guru says:
If I led you to believe I have issues with valleys on steel roofing over purlins I somehow took you astray.

In order to have a successful valley, these steps are followed:

Main roof is framed up, including purlins across area where reverse gable will intersect. 2×12 blocking is then placed between main roof purlins, centered on what will eventually be the middle of the valley. This provides a landing point for intersecting roof purlins from reverse gable (next to be installed). Once these purlins are in place, any reflective radiant barrier (RRB) is installed (I prefer using roof steel with Integral Condensation Control to a RRB). Valley flashing is then installed. We furnish Emseal® self-expanding foam closures to seal between valley flashing and roof steel, following slope of valley flashing. Roof steel is then applied and you are buttoned up tight.

Most challenging parts of assembly are cutting intersecting roof purlins (besides cut being at a 26.6 degree angle along wide face of purlin, cut also needs to be done at 26.6 degrees from perpendicular to compensate for slope of intersecting purlins from vertical) and cutting roof steel at valley to end up with a nice straight line up valley. Neither one is actually beyond most people’s abilities.

There really is no structural advantage to solid sheeting your roof and even the best of shingles have a very poor warranty and I cannot, in all good conscience recommend them as a practical design solution.

For extended reading on Emseal® closures: https://www.hansenpolebuildings.com/2016/03/emseal-self-expanding-sealant-tape-closures/

What to do About a Leaking Cupola

What to do About a Leaking Cupola

Hansen Pole Buildings has always used prefabricated cupolas manufactured by MWI – I even have one on top of my own house, so they must be good stuff! Only once have I ever gotten feedback from a client to tell me their cupola was leaking. In their particular case, it was because their builder had installed the cupola and its flashing first directly on top of the roof purlins. The builder had then butted the steel roofing and the ridge cap up against the cupola!

I know, it sounds counter intuitive and it was. Most of the time the Law of Gravity says, “water runs down hill”.

One of my readers recently wrote to tell me the cupola on the roof of his Cleary Building leaks every time it rains and he was looking for a fix.

Here was my advice:

Now I am not your average pole barn owner – and I don’t like exposed caulking. I’d be replacing what is there with a brand new cupola with a universal base. Besides what comes with the cupola kit, you would need a hand full of stitch screws the color of the base and two outside closures to put beneath the downhill edges of the base. Yes, it is going to be an investment, however it will solve the problem and look nice and new.

Assuming you want to fix what is there, here is the mission – find where it is leaking. Requires a hose and someone to stand inside and tell you when the water starts coming through. Begin with the flashings on the downhill edges, run a pretty good stream of water onto them (one at a time) for a minute or so. Even if the leak is along one of them, keep checking along the way, as it could be multiple points. Next do the flashing on the ridge cap sides. Then each side of the cupola individually (letting the water run down from the cupola roof).

If there is a leak, it should have shown up in the hose test. With the leak isolated, you can do a repair with the best silicone caulking money can buy. If one of the edges of the flashing is not sealed to the roof, Emseal AST expanding closures work quite well to fill those gaps. https://www.hansenpolebuildings.com/2016/03/emseal-self-expanding-sealant-tape-closures/