From Newsgroup: rec.crafts.metalworking

Does anybody know of a gasketed roofing screw that both shades the gasket from UV and tranmists clamping force around (not through) the gasket material?

All the gasketed screws I've seen leave the rim of the gasket exposed. That means light reaches the gasket obliquely and the clamp force is limited by
the compressive strength of the gasket.

The washer needs to be a simple cup, _slightly_ shallower than the gasket. Tightening the screw would force the gasket against the mounting suface, compressing it inward to seal the screw shank. When the rim of the cup
hits the surface the load moves to the washer and light entry is blocked.

I can't be the first one to think of this. If anybody knows where to look please post.

Thanks for reading,

bob prohaska



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From Newsgroup: rec.crafts.metalworking

On Sun, 19 Apr 2026 19:26:52 -0000 (UTC)
bp@www.zefox.net wrote:

<snip>

The washer needs to be a simple cup, _slightly_ shallower than the gasket. >Tightening the screw would force the gasket against the mounting suface, >compressing it inward to seal the screw shank. When the rim of the cup
hits the surface the load moves to the washer and light entry is blocked.

I can't be the first one to think of this. If anybody knows where to look >please post.

Maybe buy the washers separately, like these?

https://www.amazon.com/Sealing-Washers-Stainless-Neoprene-Bonded/dp/B0BL37LWKH/ --
Leon Fisk
Grand Rapids MI

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From Newsgroup: rec.crafts.metalworking

On 4/19/2026 12:26 PM, bp@www.zefox.net wrote:

Does anybody know of a gasketed roofing screw that both shades the gasket from
UV and tranmists clamping force around (not through) the gasket material?

All the gasketed screws I've seen leave the rim of the gasket exposed. That means light reaches the gasket obliquely and the clamp force is limited by the compressive strength of the gasket.

The washer needs to be a simple cup, _slightly_ shallower than the gasket. Tightening the screw would force the gasket against the mounting suface, compressing it inward to seal the screw shank. When the rim of the cup
hits the surface the load moves to the washer and light entry is blocked.

I can't be the first one to think of this. If anybody knows where to look please post.

Thanks for reading,

bob prohaska

If the edge degrades does it matter? Also, if the washer is dish shaped
then you may have a "cutting" edge that could dig into the sheeting.

I'm not claiming either of those things is true. Just that you should consider them.
--
Bob La Londe
CNC Molds N Stuff
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From Newsgroup: rec.crafts.metalworking

"Leon Fisk" wrote in message news:10s3coo$4ncn$1@dont-email.me...

On Sun, 19 Apr 2026 19:26:52 -0000 (UTC)
bp@www.zefox.net wrote:

<snip>

The washer needs to be a simple cup, _slightly_ shallower than the gasket. >Tightening the screw would force the gasket against the mounting suface, >compressing it inward to seal the screw shank. When the rim of the cup
hits the surface the load moves to the washer and light entry is blocked.

I can't be the first one to think of this. If anybody knows where to look >please post.

Maybe buy the washers separately, like these?

https://www.amazon.com/Sealing-Washers-Stainless-Neoprene-Bonded/dp/B0BL37LWKH/ --
Leon Fisk
Grand Rapids MI

-----------------------------

Thanks, that looks like a very good solution for my corrugated roofs too.

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From Newsgroup: rec.crafts.metalworking

On 4/19/2026 1:08 PM, Leon Fisk wrote:

On Sun, 19 Apr 2026 19:26:52 -0000 (UTC)
bp@www.zefox.net wrote:

<snip>

The washer needs to be a simple cup, _slightly_ shallower than the gasket. >> Tightening the screw would force the gasket against the mounting suface,
compressing it inward to seal the screw shank. When the rim of the cup
hits the surface the load moves to the washer and light entry is blocked.

I can't be the first one to think of this. If anybody knows where to look
please post.

Maybe buy the washers separately, like these?

https://www.amazon.com/Sealing-Washers-Stainless-Neoprene-Bonded/dp/B0BL37LWKH/

Good catch. Makes me wish Usenet had a thumbs up button.


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--
Bob La Londe
CNC Molds N Stuff
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From Newsgroup: rec.crafts.metalworking

Bob La Londe <none@none.com99> wrote:

On 4/19/2026 12:26 PM, bp@www.zefox.net wrote:

Does anybody know of a gasketed roofing screw that both shades the gasket from
UV and tranmists clamping force around (not through) the gasket material?

All the gasketed screws I've seen leave the rim of the gasket exposed. That >> means light reaches the gasket obliquely and the clamp force is limited by >> the compressive strength of the gasket.

The washer needs to be a simple cup, _slightly_ shallower than the gasket. >> Tightening the screw would force the gasket against the mounting suface,
compressing it inward to seal the screw shank. When the rim of the cup
hits the surface the load moves to the washer and light entry is blocked.

I can't be the first one to think of this. If anybody knows where to look
please post.

Thanks for reading,

bob prohaska

If the edge degrades does it matter? Also, if the washer is dish shaped then you may have a "cutting" edge that could dig into the sheeting.

I think something deeper than a dish will be needed to give the needed compliance. Probably twice the depth-to-diameter ratio of most such
parts.

I'm not claiming either of those things is true. Just that you should consider them.

Eventually light getting under the edge will degrade the gasket. It's unclear if there's enough meat on the gasket to seal against a screw that fits the hole. The idea is close, but the proportions don't look quite right and
there's no good illustration.


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From Newsgroup: rec.crafts.metalworking

On 4/19/2026 12:26 PM, bp@www.zefox.net wrote:

Does anybody know of a gasketed roofing screw that both shades the gasket >> from
UV and tranmists clamping force around (not through) the gasket material?

--------------------------

Is this raised seam roofing? I use corrugated galvy and plastic with the screws in the tops of ridges and not tightened enough to distort. It covers spaces that don't need to be completely waterproofed, warm humid early
spring weather with snow still on the roof causes considerable condensation
to drip from the underside, enough that the purlins were sliced from PT.

Areas that I clear with a DIY snow rake have wafer head screws that the
rubber door seal bottom edge slides over.

The replacement washers I punched from red rubber plumbing sheet crumbled in sunshine but held up under the screw heads.

The 4' wide roof that partly covers the deck was hinged to the house and
hangs vertical for repairs, I can easily reach all of it from a stepladder. The larger shed roof has every third 2' section separately framed as a removable hatch, allowing me to reach all the screws on the two fixed
sections between them. One section of the deck roof is the same for easy
roof access.

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From Newsgroup: rec.crafts.metalworking

On 4/19/2026 12:26 PM, bp@www.zefox.net wrote:

Does anybody know of a gasketed roofing screw that both shades the gasket >> from
UV and tranmists clamping force around (not through) the gasket material?

I think the gasket washer allows the roof to expand and contract while still sealing.

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From Newsgroup: rec.crafts.metalworking

bp@www.zefox.net wrote:

I think something deeper than a dish will be needed to give the needed compliance. Probably twice the depth-to-diameter ratio of most such
parts.

Sorta found what I'm looking for. It's called a "dome cap screw", https://www.metalroofingscrews.com

The headcap is die-cast. That's a little surprising.

Thanks for reading,

bob prohaska

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From Newsgroup: rec.crafts.metalworking

On Sun, 19 Apr 2026 19:26:52 -0000 (UTC), bp@www.zefox.net wrote:

Does anybody know of a gasketed roofing screw that both shades the gasket from >UV and tranmists clamping force around (not through) the gasket material?

All the gasketed screws I've seen leave the rim of the gasket exposed. That >means light reaches the gasket obliquely and the clamp force is limited by >the compressive strength of the gasket.

The washer needs to be a simple cup, _slightly_ shallower than the gasket. >Tightening the screw would force the gasket against the mounting suface, >compressing it inward to seal the screw shank. When the rim of the cup
hits the surface the load moves to the washer and light entry is blocked.

I can't be the first one to think of this. If anybody knows where to look >please post.

Thanks for reading,

bob prohaska

The only problem is you just made a hole punch. Guaranteed to cut the
steel roofing in a short time - leaving big holes and a loose roof
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From Newsgroup: rec.crafts.metalworking

Clare Snyder <clare@snyder.on.ca> wrote:

On Sun, 19 Apr 2026 19:26:52 -0000 (UTC), bp@www.zefox.net wrote:

Does anybody know of a gasketed roofing screw that both shades the gasket from
UV and tranmists clamping force around (not through) the gasket material?

All the gasketed screws I've seen leave the rim of the gasket exposed. That >>means light reaches the gasket obliquely and the clamp force is limited by >>the compressive strength of the gasket.

The washer needs to be a simple cup, _slightly_ shallower than the gasket. >>Tightening the screw would force the gasket against the mounting suface, >>compressing it inward to seal the screw shank. When the rim of the cup
hits the surface the load moves to the washer and light entry is blocked.

I can't be the first one to think of this. If anybody knows where to look >>please post.

Thanks for reading,

bob prohaska

The only problem is you just made a hole punch. Guaranteed to cut the
steel roofing in a short time - leaving big holes and a loose roof

Only if the bolt is grossly overtightened. Correct tension on sealing
fasteners is critical, surface quality of the mating materials matters
as well. Intallation manuals harp on the issue endlessly.

I realize there's no idiot-proof solution to the problem.

Thanks for writing,

bob prohaska


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From Newsgroup: rec.crafts.metalworking

On Tue, 21 Apr 2026 15:43:48 -0000 (UTC), bp@www.zefox.net wrote:

Clare Snyder <clare@snyder.on.ca> wrote:

On Sun, 19 Apr 2026 19:26:52 -0000 (UTC), bp@www.zefox.net wrote:

Does anybody know of a gasketed roofing screw that both shades the gasket from
UV and tranmists clamping force around (not through) the gasket material? >>>
All the gasketed screws I've seen leave the rim of the gasket exposed. That >>>means light reaches the gasket obliquely and the clamp force is limited by >>>the compressive strength of the gasket.

The washer needs to be a simple cup, _slightly_ shallower than the gasket. >>>Tightening the screw would force the gasket against the mounting suface, >>>compressing it inward to seal the screw shank. When the rim of the cup >>>hits the surface the load moves to the washer and light entry is blocked. >>>
I can't be the first one to think of this. If anybody knows where to look >>>please post.

Thanks for reading,

bob prohaska

The only problem is you just made a hole punch. Guaranteed to cut the
steel roofing in a short time - leaving big holes and a loose roof

Only if the bolt is grossly overtightened. Correct tension on sealing >fasteners is critical, surface quality of the mating materials matters
as well. Intallation manuals harp on the issue endlessly.

I realize there's no idiot-proof solution to the problem.

Thanks for writing,

bob prohaska

if the "cup washer" of the screw is tight rnough not to let ANY light
into the elastomer it is close enoughto the dheet metal that any
compression of the elastomer will allow movement of the sheet metal,
whichWILL eventually compromisethe sheet metal They are designed the
way they are for a reason - and the elastomer washer is not
deteriorating enough from sunlight to affect the seal of the washer or
the hold of the screw / sheet metal. You are trying to solve a
basically non existing problem, and causing an almost definite one in
it's place. They have been using those sheet metal screws for ofer 50
years - and they work. The old "lead head" nails were a different
story - the pulled out of the wood in a strong wind and then the rood
leaked (not much - they were on the top of the rifges - but enough to
wet the joists, causing them to rot a bit, causing the nails to loosen
more - etc) I've seen wind stormes lift sheets from barn roofs that
were nailed - it takes a tornado to take a screwed down roof - and
then it USUALLY takes the joists along with the steel.
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