Is additional weight of installing rubber roof tiles a concern? 1

[EvanVanVan]

I posted this on doityourself.com but this might be a better forum for my question.

I'm looking to protect the (flat) roof membrane on the roof deck of the duplex home we just built. I found this product which sounds perfect for my needs:

https://www.rubberflooringinc.com/in...oof-tiles.html

- There are several different manufacturers/options this was just first/easiest link.

Recommended Uses – Deck Top Roof Tiles are versatile and can be used in a variety of indoor and outdoor settings. Ideal for high-rise decks and rooftops... With their grooved bottom design, these tiles allow for water to easily flow under the tile, protecting fragile waterproof roof membranes...

My concern now, is they're 21-24 lbs per 2x2 tile depending on the manufacturer. The one deck would needs 55 tiles for a total of 1,155 lbs. That sounds heavy AF to put on a roof without research.

My other deck I had structurally engineered and framed to support a hot tub (4,600 lbs alone) which it currently holds. It would need 40 tiles for an additional 840 lbs.

I was thinking I should probably go back to the structural engineer regarding the tiles. But then realized I'm forgetting the weight is quite spread out over the entire 223 sq ft deck. Really these times are only adding 6 psf?

Thoughts?

Ty

 

[DTS419]

I was thinking I should probably go back to the structural engineer regarding the tiles.

Answer

 

[ChorasDen]

Is additional weight of installing rubber roof tires a concern?

It might be, but we are not in a position to answer that, your best option is to consult back with the project engineer of record who is familiar with the design, and ask them if the system is sufficient for this additional loading.

 

[JoshPlumSE]

Yeah, you probably should let your structural engineer know. Personally, I don't think it will be much of a problem. But, it makes sense to let him know. I don't know what the benefit would be with not letting him (or her) know.

 

[EvanVanVan]

Damn, I knew I was going to get a bunch of responses advising to play it safe and talk to the engineer!

Unfortunately, it's not like the engineer was really "a part of the project." All of these duplexes going up in my area are carbon copies no matter the builder or the architect. The structural engineer may or may not have signed off on an original version of the (carbon copy) plans years ago, but now, probably only gets consulted for major changes.

Even getting the architect to release the cad files to "his" engineer (that I had hired privately), to design plans to support the hot tub was an incredibly frustrating process.

It'll probably cost thousands of dollars just to ask him to research whether the existing roof can support the extra weight of the tiles. I was really hoping when I realized it was only going to be 5-6 lbs per square foot, that it was s a negligible amount...

 

[EvanVanVan]

FWIW this is what I've got from the plans...in New Jersey

 

[ChorasDen]

This should go back to the engineer who was hired for the project, but then again, others may have been involved. Specifically, is the roof trussed, and are the trusses deferred submittals? If so, the engineer may not be able to easily analyze the roof truss system, and short of re-evaluating the existing dead load, this may also need to go back to the truss supplier to ensure the nail plates and chords are sufficient for additional loading. These situations are usually much cheaper to address during design, rather than after construction.

 

[straub46]

The IEBC (International Existing Building Code) says reroofing material 3 psf or less is acceptable for Alterations of existing buildings (generally without need for analysis). Your 6 psf is double that allowable. You should have it checked by your engineer.

Go Bucks!

 

[EvanVanVan]

Thanks, guys.

@straub46, great post! Thank you for that information.

 

[Tomfh]

Deduct it from your roof live load, and limit remaining occupancy accordingly.

 

[IRstuff]

If it were purely a roof and designed to code, it probably wouldn't be a major problem, since the typical soaking wet roofing tile is on the order of about 6 lb/sf and usually has plywood underlayment. The only thing I typically see is some diaphragmic sagging on house roofs, which is why I personally got a metal roof.

However, you imply your roof was designed for entertainment, or at least, lots of people walking on it, but the loading schedule didn't allow for the same loading as your floor load, which seems problematic to me, since the membrane structure eats into some of the dead load, but you likely have a little headroom, assuming your membrane structure is less than 3 lb/sf

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[EvanVanVan]

lol sales person doesn't think it is such a big deal lol

The builder was actually asking us if we wanted "tiles" installed on the roof, but he was Russian and English wasn't his first language so there would be miscommunications. We thought he was talking about ceramic tiles and grout, had no idea how that would work.. He may very well have been talking about these type tiles lol.

This is what I've got in the ceiling of the 2nd floor under the roof deck:

Here's some roof deck porn framed to support a hot tub lol: (The other deck does not have all of the additional LVLs)

 

[LittleInch]

A few things.

1 can you edit your title please to read tiles not tires....

2 Not sure what you expected here, but this is an engineer to engineer set of forums not a service for homeowners to do their own design.

3 Ultimately is up to you. Pay the money for the right service and expertise or take a risk, lay the tiles then wonder in 6 months time why you have cracks in the ceiling and a low spot in the centre of your deck.

Each deck or flat roof will be different and whilst your roof deck will almost certainly not collapse, it could get springy to walk on or deflect in places so it's a serviceabilty limit which comes into play.

This is not a free design service.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[EvanVanVan]

1. Never noticed the title typo. Thanks.

2/3. Just advice and I got that, thanks!