Advice on buildng roof decks -- to suspend or not to suspend?
We want to build a roof deck on a 4-story brownstone, but don’t know if we need to have it placed on steel beams or if we can build directly on the roof. I’m getting contradictory advice form deck builders on this. If we stick to a wood deck covering 20% of the roof, can…
We want to build a roof deck on a 4-story brownstone, but don’t know if we need to have it placed on steel beams or if we can build directly on the roof. I’m getting contradictory advice form deck builders on this. If we stick to a wood deck covering 20% of the roof, can we do it without the steel and avoid that cost, or is that risking damage to the building? Anyone out there have experience with this and can make a suggestion? And any sense of whether one or the other is more likely to improve the resale value of the building? Thanks!
please consider any type of roof problem you may encounter – leak -etc. It is best to make the deck removable. its a pretty expensive process to remove – repair and rebuild
Yes for a roofdeck you typically run the steel from one party wall to the other. Each building’s part of the party wall is typically 8″ or so thick (two bricks) so the ends of the steel have plenty to bear on.
how is the steel installed? is it placed across from each party wall? and what if you share the party wall with a neighbor?
thanks
You don’t necessarily need a crane and street closing to add steel for a roof deck. I recently did a project with a roof deck that had to be reinforced for a large hot tub, and a tree in front of the property precluded any crane to get the steel up there to the roof. We had the steel sized and engineered to be brought up by hand in three sections each beam, then connected with high strength bolts to make the longer beam once up on the roof.
Also I’d warn against the Trex mentioned above, and similar composite products, these come with some serious downsides. They do not live up to their marketing hype, particularly in durability problems. Unlike wood, which has excellent fastener “memory”, composites gradually lose hold on nails and screws in the long term. After 3-4 years, parts that flex a bit like a rail you might lean on eventually rock loose, so you end up re-attaching parts all the time. Frustrating. Plenty of discussion on this material in Fine Homebuilding’s forum for those interested.
Didn’t put ours on I-beams, but the builders did use a crane to bring in the materials. No permit, just came on the right day/time for street sweeping so they could avoid cars.
We used and I’d advise you to choose a composite product (Trex, etc.). The UV and weather like today’s is brutal up there on wood. even treated lumber will splinter very quickly. It may not rot, but it will be no fun to walk on real wood in a couple of years.
We sunk our planters too. You don’t need I-beams to do so. You just need a deck raised off the surface on a sub-structure. Every deck should have one anyway so that the roof material is protected.
We decided to put a wood (cedar) deck up on steel beams for a number of reasons, including (i) ability to cover more than 20% of the roof with flammable material, and (ii) freedom from worrying about how much weight was on the roofbeams. Once it was built, we felt that being up on the beams had the added effect of making the deck feel more substantial, which is to say that it felt more like you were on a real, solid deck and not just on a few pieces of lumber thrown onto a roof.
Going with steel also enabled us to “sink” planters below the deck level by building planter boxes that rested on the lower part of the i-beams. The dirt level in the “sunken” planters was just barely above the deck level.
No street closing for the crane was needed.
how about just putting rubber pavers right on the roof? they will protect the roof and allow for drainage.
do you actually need to have a new structure built?
First, you’d want someone intelligent to confirm that the roof, which is usually not designed to support heavy loads, can support the deck you plan, your friends, and your bbq grill.
If it can’t, then you’d need steel beams. And a crane rental. And street closing permits for the crane.
After that, you can worry about more mundane things, like the fire code. AFAIK not more than 20% of the sft area of the roof can be used for flammable materials, like a wood deck.
Denton
Recently added a roof deck using process described by 1:07 – was part of larger re-roofing project. Don’t know fire regs, but we filed with DOB and no issue was raised about distance from neighbors, which is less than 3 feet. Did use a recycled plastic deck lumber.