roof deck: could use advice from the brain trust

[Tishabet]

Let me start off by apologizing for what is sure to be a long post!

OK guys, I'm looking for advice on what to do with my roof as well as how I should go about doing it. Here's the deal:

My wife and I have been in our condo for about four years now, and one of the coolest features of the place is the roof access. We own the top floor of our building and have a spiral staircase up to the roof along with exclusive rights and access. In the more temperate months, we are up there 2-3 times per week and often grill and eat dinner there, and I'll often head up for a late night cigar and stargazing as well. When we have guests or parties people love spending time up there.

Currently the roof is just... a roof. The roof surface is a type you can walk around on (I believe it's "modified bitumen" based on some brief research) and isn't so bad, though it does get very hot and will make the bottoms of your feet impressively dirty. The entire roof has a slight pitch dropping to a single drain on the inside wall. Total surface is roughly 1200 s.f.

We've decided that it's time to take the plunge and spruce things up on the roof, both for our enjoyment and for future resale, although the latter concern is more of a "let's not lose money" type of concern than a "let's make a profit" type. The most obvious thing to do is to build a roof deck covering at least some of the roof, and maybe some low wattage lighting (currently there is no lighting up there, though we do have power). Although I have wrenching skills and have helped build a "traditional" deck, I think this project is going to be performed by a pro. That being said, I still have a bunch of questions and concerns, and I figured the Pelican brain trust could help!

Roof deck engineering
At face value building a roof deck like this one should be dead easy... a rectangular one-level deck. However, there are a multitude of potential problems swirling in my head... how to frame/support something like this? Is the roof able to support the load, and how do I find out? Is it OK to have load resting on a roof surface? If not, is there some way to support the deck entirely from the external brick walls? How can I ensure reasonable access to the roof itself for future maintenance and repair?

Roof surface
The roof is five years old, but is already creating some "bubbles" that are like a pillow of air (see pics) as well as crazing. Should I do something to the roof before covering it with the deck e.g. apply elastomeric surface? Is the existing roof surface material suitable to either be under the deck or potentially supporting some sort of footings?

Contractors
I've never dealt with a contractor before in my life... I've read up a bit on the "gotchas" regarding insurance and the bidding process, but that's about it. Should I try to find one contractor to do the whole shebang, or a roofer to prepare and weatherproof footings and a general contractor to build the deck or...?

Bang for buck
The wife and I have saved up about a decent 911SC worth of funds. Where do you guys think we should concentrate our spend?

[deanp]

Why not go with an open style deck hockey / garage floor surface. Will get your feet off the roof material, water will flow through to the roof and still drain and you can pull it up yearly to spray/clean underneath. It would also make access to the roofing material easy for repair.

[Tishabet]

From the hatch, looking toward the elevator house


From the elevator house, looking toward the hatch

[Tishabet]

Originally Posted by deanp

Why not go with an open style deck hockey / garage floor surface. Will get your feet off the roof material, water will flow through to the roof and still drain and you can pull it up yearly to spray/clean underneath. It would also make access to the roofing material easy for repair.

Hi Dean,

we looked into a similar solution in the form of snap-together decking tiles (you can see some under the BBQ in the pics above). Unfortunately they seem to bond with the roof surface after a month or two, and as they sink they no longer have the space underneath to aid in drainage.

That being said, I have considered laying down some sort of floating membrane (like anti-weed membrane) and allowing tiles/hockey surface to float on top. Definitely one option!

[Tishabet]

Here's a shot of the roofing surface and crazing; that's my wedding ring for scale

Here is one of the larger "bubbles." It's air tight and probably rises 3/4 to 1 inch above the surrounding roof.

[Tishabet]

This is just to show you why we like it so much up there... great views of Lowell

[911Rob]

Hey Grant,
Great space you have there!

I'll chime in some canadian two cents worth:

I would patch the existing roof with some filler/sealer for sure. Fill the cracks.

I'd scrap your idea about a deck; too many liabilities and too much cost imo.

Try building some removable 8'x8' cedar slat flooring panels; something like this pic:


You can build the panels with a very low profile, they can be built on some wide sleepers which will still allow for drainage below and load spreading over the existing roofing. You'll want to avoid any kind of point loading. This will also benefit the existing roof because the most damage to a roof is from the sun, so this can act as a ballast and protect the membrane, extending its life considerably.

I would spend some money on lighting, it will enhance the area for evening use. Forget the solar stuff and do it right.


I'd clean things up as much as possible; painting the doors, trims, etc. It looks like you may have a plumbing vent stack coming up behind one of the pyramid skylights; you should extend that up about 9 feet; it probably emits sewer gas smells? not pleasant for a deck? Probably against code too?

Measure everything to the inch and draw it all out. When you hire a contractor get referrences and give them the plans. Show exactly how you want things done. The cedar look is awesome for decks; so do the floor, add some planters, built in benching, maybe some columns/posts for lighting, hanging baskets?

Then you'll have some money left over too.

Hope this helps?

[stomachmonkey]

That is one kick ass space.

I'd buy it for that alone.

Am by no means a contractor or engineer but with all that brick around can you anchor hangers in them and run stringers to lay a floor on?

I'd be a bit worried about raising the floor too much. Don't want guests falling over the wall.

Can you do gravel over the roof surface with pavers to create walking paths? I think the gravel would not upset the drainage, is easy to DIY. Could make a very Zen rock garden type of space.

Have you considered a retractable awning anchored in the back brick wall?

Lighting should be easy.

[dad911]

Habitable roof decks I have been on have been fiberglass.

[Porsche-O-Phile]

Love the setting - great for sure.

If the association doesn't care what you do, I'd look into wood slats on top of the existing surface, just have it filled and patched first to ensure watertight protection. Things to check include weight (anything added to a roof adds weight and this can be a real problem if not investigated), flashing details at edges, drainage (perfectly flat, horizontal decks are a BAD idea - need to have drainage min. 1/8" per 1'-0", preferably 1/4" per 1'-0"), etc. When I get back that way next if you're around I'd love to check it out for you. Maybe I could look into working something up if you want - I'm not doing much else these days and it'd be a good design exercise... Lemmee know.

[ruf-porsche]

Originally Posted by Tishabet

Here's a shot of the roofing surface and crazing; that's my wedding ring for scale

Here is one of the larger "bubbles." It's air tight and probably rises 3/4 to 1 inch above the surrounding roof.

That's not crazing, it is known in the industry as alligatoring. The roof needs to be repaired or replaced in the near future. You should see what the condo association will allow you to construct since the roof is normally considered a common element.

You don't want to construct a deck and have the association tear it apart to repair the roof.

[Jims5543]

Your first move would to be to hire a structural engineer to look at the construction and advise you if any load can be put on the trusses below.

Then go from there. I would imagine a good engineer could design a deck for you or suggest an architect that can do it.

You may also be able to get the original building plans from the local courthouse. It might take a few phone calls but they should be scanned onto microfilm. You should be able to purchase a copy.

While you there, pay a visit to the building dept and see if a permit / inspections will be needed.

Those would be my first steps before even talking to a contractor.

[jyl]

Flat roof on the East Coast (I think) - wouldn't it be engineered to take quite some weight, thinking snow and ice load?

[stomachmonkey]

Originally Posted by jyl

Flat roof on the East Coast (I think) - wouldn't it be engineered to take quite some weight, thinking snow and ice load?

True, but snow/ice AND deck?

[javadog]

Originally Posted by jyl

Flat roof on the East Coast (I think) - wouldn't it be engineered to take quite some weight, thinking snow and ice load?

You'd think so but keep in mind this looks like an old building. Whi knows what standards/codes were followed when it was built? I have done some work in these types of buildings and the quality of the original construction sometimes is not what you'd get today. In many cases, it's pretty bad.

JR

[futuresoptions]

If it were me, I would coat the roof in a white ceramic coating available at Home Depot etc... This would seal the existing damage, buying you a little time... it is fairly durable and a little cleaner on the feet... would also reflect alot of heat... this could be a quick / low cost solution until you hire an architect etc....

[Zeke]

That's a pretty large space for anything consistent. I think I'd design the roof top into zones and use different media area by area with some repetition to tie it all together.

You could use outdoor carpet in some areas to keep it cleaner. Some raised areas (wood decking) might serve as a place to park the lounge with maybe a bench at the perimeter with lift top storage. And some areas can just be coated with a lighter color, like the BBQ part for fire concerns.

Think along the lines of how oriental rugs look placed on hardwood floors and how furniture is sometimes arranged in small groups in a large room.

The existing roof must be repaired and sealed.

[ruf-porsche]

Originally Posted by jyl

Flat roof on the East Coast (I think) - wouldn't it be engineered to take quite some weight, thinking snow and ice load?

The use of the original roof was just a roof, but now they are using it as habitable space. The design load of a habitable space is different from an unhabitable space. What if the owner decides to install a hot tub?

[Hugh R]

Look at the new synthetic lumber, it seems to be lighter and very weather proof. No staining or annual maintenance required.

[Normy]

I'm not sure how much help I can give you on your roof, but damn dude! That's cool condo!

N!