Jump to content
Sign in to follow this  
Jim Baird

Boot flange fastening

Recommended Posts

Thanks, Jim.  My quick research just showed more than one how to vid saying to place screws no more than 1 1/2 inch apart.

I am from the common sense generation.  I used these flanges on this kind of roof 20 yrs ago and only used a screw in each corner.  Am pretty sure they have not leaked.

Common sense tells me that minimizing holes you punch in a roof is the best way to do it.

Speaking of common sense, metal roof panels with this profile are also supposed to be fastened on the flats, not on the ridges.  I fastened mine on the flats, but I have seen many installations where the installer overruled the directions and put screws on the ridges.  I can only think the engineers that decided the flats are where screws should go were worried about resistance to uplift more than they were about leaks.

Edited by Jim Baird
added comment

Share this post


Link to post
Share on other sites
13 hours ago, Jim Baird said:

Thanks, Jim.  My quick research just showed more than one how to vid saying to place screws no more than 1 1/2 inch apart.

I am from the common sense generation.  I used these flanges on this kind of roof 20 yrs ago and only used a screw in each corner.  Am pretty sure they have not leaked.

Common sense tells me that minimizing holes you punch in a roof is the best way to do it.

Speaking of common sense, metal roof panels with this profile are also supposed to be fastened on the flats, not on the ridges.  I fastened mine on the flats, but I have seen many installations where the installer overruled the directions and put screws on the ridges.  I can only think the engineers that decided the flats are where screws should go were worried about resistance to uplift more than they were about leaks.

On the 12 inch profile we have down here, they are fastened once on the crest (where the mastic is applied) and once in the field.  That profile you have has a narrow crest, so I'm not sure what's correct.

Edited by Marc

Share this post


Link to post
Share on other sites
14 hours ago, Jim Baird said:

Thanks, Jim.  My quick research just showed more than one how to vid saying to place screws no more than 1 1/2 inch apart.

 

Well, those screws are no more than 1-1/2" apart . . . 

14 hours ago, Jim Baird said:

I am from the common sense generation.  I used these flanges on this kind of roof 20 yrs ago and only used a screw in each corner.  Am pretty sure they have not leaked.Common sense tells me that minimizing holes you punch in a roof is the best way to do it.

Common sense tells me that minimizing holes you punch in a roof is the best way to do it.

 

That would be wrong with this kind of boot. The extremely malleable metal flange needs more screws. They're supposed to work by using the caulk to form a gasket - like an oreo cookie. If you don't have enough screws, you can't compress the caulk. Too many screws in this particular location really won't hurt anything. 

14 hours ago, Jim Baird said:

Speaking of common sense, metal roof panels with this profile are also supposed to be fastened on the flats, not on the ridges.  I fastened mine on the flats, but I have seen many installations where the installer overruled the directions and put screws on the ridges.  I can only think the engineers that decided the flats are where screws should go were worried about resistance to uplift more than they were about leaks.

It's an old argument with a lot of myth baggage. The purpose of the screws is to secure the roofing panels to the deck. They need to be on the flats. This doesn't make leaks more likely. I'd love to see a set of manufacturer's instructions that say to put the fasteners on the ridges. As Erby pointed out, getting them just tight enough but not too tight is very difficult to do consistently. On the other hand, it's easy to consistently tighten the screws on the flats - and if they're consistently tight, they won't leak. 

Share this post


Link to post
Share on other sites

The manufacturer's rec I saw on these flanges said screws should be no more than 1 1/2 inches "apart".  It did not say "on center".  With a big fat screw head like these, 1 1/2 on center becomes about 3/4 inch apart. 

I am sure you will not see a rec that says to screw panels on thru the ridges.  There is likely lots of loss of fastening power with that way.  

Share this post


Link to post
Share on other sites
On 9/14/2018 at 5:25 AM, Jim Baird said:

The manufacturer's rec I saw on these flanges said screws should be no more than 1 1/2 inches "apart".  It did not say "on center".  With a big fat screw head like these, 1 1/2 on center becomes about 3/4 inch apart. 

 

Sure. That's fine. No more than 1-1/2" apart makes sense. You can have them less than 1-1/2" apart without hurting anything. 

Share this post


Link to post
Share on other sites

I'm the sure that installer would say that more must be better.  If the roof panels outlive the boots, boot replacement might be a challenge the way that self tappers turn the hole edges up and down.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×