Ventis cathedral box/adapter junction...silicone?

[CenterTree]

Using Ventis (Olympia) Class A and double-wall stove pipe.

Got the cathedral ceiling square support box installed. Flat ceiling in living room/stove room.

While trying to place the roof flashing, and center and plumb the first section of class A, I am finding it difficult to get that first piece centered within the top of the flashing. The reason is that the universal adapter(already attached to the down end of the class A), sits on the top inside of the support box and causes enough wobble making it hard to get the pipe plumb.

And what actual is suppose t hold this heavy class A pipe in it's plumb position? I will end up with a roof brace, but is that all that keeps the pipe firm? Seems odd.


Two main questions:::

Do I use silicone where the adapter meets the inside of the support box? Is it needed there?

How do I keep the first piece of class A straight so I can attach the flashing and move on?

 

[bholler]

Using Ventis (Olympia) Class A and double-wall stove pipe.

Got the cathedral ceiling square support box installed. Flat ceiling in living room/stove room.

While trying to place the roof flashing, and center and plumb the first section of class A, I am finding it difficult to get that first piece centered within the top of the flashing. The reason is that the universal adapter(already attached to the down end of the class A), sits on the top inside of the support box and causes enough wobble making it hard to get the pipe plumb.

And what actual is suppose t hold this heavy class A pipe in it's plumb position? I will end up with a roof brace, but is that all that keeps the pipe firm? Seems odd.


Two main questions:::

Do I use silicone where the adapter meets the inside of the support box? Is it needed there?

How do I keep the first piece of class A straight so I can attach the flashing and move on?
View attachment 246607 View attachment 246608

The box should be plumb. The adapter should be attached with screws so it stays square. If you do that the pipe will sit plumb. Then the support bracket will hold it there.

And no silicone there no.

 

[CenterTree]

The box should be plumb. The adapter should be attached with screws so it stays square. If you do that the pipe will sit plumb. Then the support bracket will hold it there.



And no silicone there no.

? What do you mean by "support bracket"? You mean the roof brace will hold it all in place?
Or do you mean the cathedral support box?.... Is this whole Class A pipe relying on gravity to hold it firm?



OK on the "no silicone". Didn't think it was needed there. Thanks.

 

[CenterTree]

The box should be plumb. The adapter should be attached with screws so it stays square. If you do that the pipe will sit plumb. Then the support bracket will hold it there.

And no silicone there no.

The adapter has no provisions for any screws to hold it to the support box. Now it does have the 3 screws that attach it to the end of the Class A pipe. Is that what you mean? Thanks.

 

[bholler]

? What do you mean by "support bracket"? You mean the roof brace will hold it all in place?
Or do you mean the cathedral support box?.... Is this whole Class A pipe relying on gravity to hold it firm?

OK on the "no silicone". Didn't think it was needed there. Thanks.

Yes the roof brace will hold it.

The adapter has no provisions for any screws to hold it to the support box. Now it does have the 3 screws that attach it to the end of the Class A pipe. Is that what you mean? Thanks.

No it doesn't get screwed to the support box gravity holds it there.

 

[begreen]

Yes the roof brace will hold it.

Or a helper with a level. Once the flashing is in place it will be steady.

 

[bholler]

Or a helper with a level. Once the flashing is in place it will be steady.

Ventis flashing is not tight to the pipe it still allows some movement.

 

[CenterTree]

Ventis flashing is not tight to the pipe it still allows some movement.

Correct, there is about 3/8 inch all the way around the pipe (at the flashing). That flashing would hold the pipe in no way with just some silicone around that area.
I talked to a tech guy at Harts Hearth & Homestead. He said a little trick is to actually add a few screws from the very top edge of the flashing into the pipe. THis would be just an added stability he said (not a full securing).. And the screws would be covered by the storm collar anyway.

 

[bholler]

Correct, there is about 3/8 inch all the way around the pipe (at the flashing). That flashing would hold the pipe in no way with just some silicone around that area.
I talked to a tech guy at Harts Hearth & Homestead. He said a little trick is to actually add a few screws from the very top edge of the flashing into the pipe. THis would be just an added stability he said (not a full securing).. And the screws would be covered by the storm collar anyway.

I really dislike doing it that way.

 

[webby3650]

Correct, there is about 3/8 inch all the way around the pipe (at the flashing). That flashing would hold the pipe in no way with just some silicone around that area.
I talked to a tech guy at Harts Hearth & Homestead. He said a little trick is to actually add a few screws from the very top edge of the flashing into the pipe. THis would be just an added stability he said (not a full securing).. And the screws would be covered by the storm collar anyway.

That works very well and doesn’t hurt a thing.

 

[bholler]

That works very well and doesn’t hurt a thing.

Yet olympia engineers say absolutely do not do it. I trust what they have to say.

 

[CenterTree]

Yet olympia engineers say absolutely do not do it. I trust what they have to say.

I wonder what the harm would be?
Only thing I can think of is expansion and contraction differences in the two different metal structures. (the flashing and the pipe)

 

[bholler]

I wonder what the harm would be?
Only thing I can think of is expansion and contraction differences in the two different metal structures. (the flashing and the pipe)

Yes the difference in expansion and contraction between the two will be great.

 

[webby3650]

Yes the difference in expansion and contraction between the two will be great.

Really? Seems pretty far fetched to me... I’ve seen it discussed on here before, I don’t buy it though. I prefer a stable chimney that isn’t bounced around in the wind.

 

[begreen]

Just hypothesizing about the eng's concern. Maybe they are concerned about the pipe's thermal expansion being transferred to the flashing with a mechanical connection? I've seen that as the reason to not screw the sections of telescoping pipe together.

 

[webby3650]

Just hypothesizing about the eng's concern. Maybe they are concerned about the pipe's thermal expansion being transferred to the flashing with a mechanical connection? I've seen that as the reason to not screw the sections of telescoping pipe together.

All the supports, Tee supports, chimney support clamp, roof brace etc.. on Hart&Cooley require screws installed after the clamp is compressed.

 

[begreen]

All the supports, Tee supports, chimney support clamp, roof brace etc.. on Hart&Cooley require screws installed after the clamp is compressed.

Do they recommend screwing the chimney pipe to the top of a roof flashing?

 

[bholler]

Really? Seems pretty far fetched to me... I’ve seen it discussed on here before, I don’t buy it though. I prefer a stable chimney that isn’t bounced around in the wind.

I will tell them they are wrong because you said so next time I see them

 

[webby3650]

I will tell them they are wrong because you said so next time I see them

We are just trying to have a reasonable discussion here. You don’t have to participate.

 

[webby3650]

Do they recommend screwing the chimney pipe to the top of a roof flashing?

Honestly I’ve never asked. The OP asked, they recommended it, although it wasn’t ventis. I’m curious if anyone has ever even tested it, I’m betting no. There’s no money in it!
We’ve got literally a few thousand chimney systems out there, I see lots of them on a regular basis and have never seen an issue, or heard of one from anybody. Other than some speculation on this site.

 

[bholler]

We are just trying to have a reasonable discussion here. You don’t have to participate.

Yes we are trying to give this poster the proper information for their install. To me the engineers who designed and tested the pipe are the best ones to ask about that. I choose to trust them.

 

[CenterTree]

I am looking around, but couldn't find it yet.... where it is that the engineers of Olympia say not to attach the flashing to the pipe?

I am thinking about the roof brace too. Wouldn't it be affected by expansion/contraction of 2 different metals also? ??

I wish it was all just black and white.

Seems like there are a lot of places within a chimney install where 2 different metals are attached via screws.

 

[bholler]

I am looking around, but couldn't find it yet.... where it is that the engineers of Olympia say not to attach the flashing to the pipe?

I am thinking about the roof brace too. Wouldn't it be affected by expansion/contraction of 2 different metals also? ??

I wish it was all just black and white.

Seems like there are a lot of places within a chimney install where 2 different metals are attached via screws.

It doesn't say anything about it in the instructions. I sat with two of them at a conference and asked them about it and many other things. It isn't different metals that is the problem. It is different heating characteristics.

 

[double-d]

Not looking to create more confusion, but, for terminology of components, there is a Roof Support - Designed to provide support for the chimney at the roof line, adjusts to any roof pitch.
Then there is a Roof Brace that attaches to the Class A pipe with long rods and attaches to the roof for stability. I believe you would want the Roof Support under the flashing?

 

[bholler]

View attachment 246628 Not looking to create more confusion, but, for terminology of components, there is a Roof Support - Designed to provide support for the chimney at the roof line, adjusts to any roof pitch.
Then there is a Roof Brace that attaches to the Class A pipe with long rods and attaches to the roof for stability. I believe you would want the Roof Support under the flashing?
View attachment 246629

No he has a support box he will need a roof brace