Third Floor Addition On Flat Roof - Building & Construction - DIY Chatroom Home Improvement Forum

Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Building & Construction


Thread Tools Display Modes
Old 02-06-2011, 10:36 PM   #1
Join Date: Nov 2010
Posts: 6
Rewards Points: 10

Third floor addition on flat roof

I'm a first time poster, so apologize in advance if I'm not following some unwritten conventions. Please be kind!

I'm living in a dream world of adding a third story to our flat roof duplex/home. I want to live on the second and third floor and continue to rent out the main floor for rental income. I've scoured the web for resources and google sketched my dream and I'm now ready to start asking some questions to see if this is really a possibility!

I fully intend to get a qualified contractor to complete the job but since I won't be able to afford to finance the reno for at least two more years, I figured I would learn as much as I can in the meantime. I'm a DIYer at heart. I even got my real estate license so i could buy my own house!

I've attached a pic of an identical house from streetview ( I don't feel comfortable using my own in case my neighbours use this resource too!). And, I've attached a nearly complete snip of my google sketch. I am not an architect and really have very little talent in the design element but, I'm happy enough with my product and at least I know if I *do* bring it to a design and build company, they'd have to give me something better.

I had a consult with a structural engineer and he is pretty confident the house can handle another floor. I will know for sure when the geotechnical engineers check the soil. At the very least, I want to add 10' out the front and change the facade so I figured I would wait until then to dig things up to determine soil capacity and the size of the footings.

The current framing is very basic. The house is 23' by 40' with a steel beam in the basement running down the center and posts every 10 feet. The load bearing wall runs down the center on both floors in the back half of the house and is offset 10':13' in the front. It is a duplex and both floors are built exactly the same. From what I can tell ( we have a leak a bedroom so we had to take off part of the ceiling) the roof is built the exact same way as the floors.

So... my questions...

1) I am hoping to make the front room pretty open concept. I will be adding 10 feet out the front of the house ( 8 feet in the recessed area) and taking the 6 feet of the current house to make one 16' x 23' living area with 10' or 11' ceilings. Any opinions as to whether the roofline shown will allow me to have an open room? or will I need a post? - I'm thinking possibly where the ridge is for the front part of the hip roof??

2) Am I naive in thinking the third floor addition part may be as 'easy' as removing the current roofing materials and starting on the wall framing?

Any and all insight is appreciated. Please pass along links or posts that you think might help. I know it will be expensive but, the alternative is taking over the main floor apartment. I'm hoping the rental income will help finance the reno!

Tear downs on this street are going for what we paid for this place two years ago so I'm pretty certain whatever we put into the house will be reflected in an assessment. Plus, we're not planning on moving so I get to enjoy it.

Attached Images


Magmo is offline   Reply With Quote
Old 02-06-2011, 10:44 PM   #2
joed's Avatar
Join Date: Mar 2005
Location: Welland, Ontario
Posts: 13,263
Rewards Points: 13,322
Blog Entries: 11

The ceiling joist may need to be increased. They were designed for a roof load not a live load of persons and furniture. This could involve tearing out the second floor ceiling. Or the work might be able to be done from above with no damage to the second floor ceiling.


joed is online now   Reply With Quote
The Following User Says Thank You to joed For This Useful Post:
Magmo (02-07-2011)
Old 02-07-2011, 09:41 AM   #3
Join Date: Mar 2007
Location: Long Island, NY
Posts: 11,188
Rewards Points: 5,336

First thing I would do is contact the building dept to see if there are(and there are)height restrictions to the structure. Look around the area for houses that have been added to, to see their relative height to the rest of the block. Sometimes you can get variances, but these will be limited in scope.
I live in a small village and this contractor framed this very large house. It was framed, sheathed and had the little branch at the peak. It sat that way for 8+ months. Then they deconstructed it down to the platform and rebuilt it shorter. Seems they built it higher then the plans called for and the village made them take it down.
The delay cost him over a year. During that time, the housing market fell out and the price he was asking($2.4 mil) was a pipe dream. It was on the market for about 18 months, before he moved in himself.
If he makes any money on the house, I'll be surprised.
Ron6519 is offline   Reply With Quote
Old 02-07-2011, 11:43 AM   #4
Join Date: Nov 2010
Posts: 6
Rewards Points: 10

Thanks Ron! The height restriction around here is 11m - enough for a decent third floor. I don't want to be too imposing though so I'm hoping to keep the front part at two stories and I would even consider stepping the back part in a little if it can be structurally sound.

Although 11 m is plenty, i don't want to piss off my neighbours. In my particular case, I think going up is better than going back. Their main living space/addition is on the back of the house and they use their backyard a lot. Our houses face west.

Thanks again for the input. It would be a nightmare to have built something and have to tear it down!


Magmo is offline   Reply With Quote
Old 02-07-2011, 12:03 PM   #5
Join Date: Dec 2010
Location: N.VA
Posts: 52
Rewards Points: 75

Not sure how you plan on handling the rental part but you may want to check with zoning and utilities.
Nucon is offline   Reply With Quote
Old 02-07-2011, 11:44 PM   #6
Join Date: Nov 2010
Posts: 6
Rewards Points: 10

Joed - checked the ceiling and it's built with 2x10s, 16 oc - no idea what type of what type of wood. The house was built in 1950. I plan on the third floor having a load bearing wall directly over the current wall on the first and second floor, which are placed directly over the steel beam in the basement. Hopefully the structure is strong enough to support another story. The only difference between the ceiling and our current floors is that the subfloor(?) also wood pieces, maybe 2x10?, run perpendicular to the ceiling joists whereas for our current floors, they are placed on a diagonal. Not sure why.

Nucon, it's currently listed with the city as a legal duplex. I'm hoping to keep it that way .

Looked into prices of exterior siding materials tonight. Ouch, since I'll likely have to cover the whole house. Can't find much on this forum about removing pebbledash. I have a feeling it won't be an easy job.

Am I in the ballpark to think that this reno will cost 125k for shell and core? It's hard to do a sf general calculation since I am building 400 sf out the front with a 200 sf footprint, and a 600sf third floor with no foundation. I realize it depends on labour costs. Min wage here is $12 an hour if that's any help. I think the going rate for a qualified carpenter is about 35 - 40/h.



Magmo is offline   Reply With Quote

flat roof , hip roof , third floor

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Replacing peaked roof with a flat roof....? earthtoned Building & Construction 2 01-21-2010 04:28 PM
Blown Insulation - Flat roof AndrewF Roofing/Siding 1 12-31-2009 06:41 PM
Flat roof related questions christy123 Roofing/Siding 8 12-09-2008 11:30 PM
Flat roof headache The Barber Roofing/Siding 7 05-17-2008 05:48 PM
Flat roof addition - Joists connected to structure via legerboard?? Rhino17 Building & Construction 2 09-01-2007 06:56 AM

Top of Page | View New Posts


Search Engine Friendly URLs by vBSEO 3.6.1