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Protecting house when removing roof

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Astone

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Discussion starter · #1 ·
Hi all, Few posts here but trying to get more involved:

Starting a new job where we are framing a 1200’ addition onto a 2400’ existing house.

Brand new roofing which calls for entire roof to be replaced with new trusses. I am struggling to see how to protect house when we rip off roof and replace with new trusses.

Going to be very rainy as I am on Vancouver Island.

Options:
1) See if truss company can redesign as an overframe. Would still need to cut some of existing roof away to allow for new trusses

2) have scaffold erected all around similar to tenting an entire house. However obviously cannot have them erect a scaffolded roof because we couldn’t drop trusses in

3) any other bright ideas?
 
#2 ·
Are you changing the pitch of the existing roof? Tearing out those trusses will obviously tear out the ceiling too, if finished.

If possible I’d sister in the new trusses along next to the existing ones, replacing the gable ends if that’s how it’s built. Much faster and cleaner


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#5 · (Edited)
Order trusses that are cut in half and designed to be "zipped" up in the field...install temp shoring down center line of trusses, do 51 % of roof, then other side....:thumbsup: A few 100.00 $ Canadian , for easier to handle trusses

Rent a "circus tent roof/tarp hung from engineered masts that are guy wired into yard(s), two masts with a ridge line to fold the tarp over, get a pro to sign off on the 30-90 day period peak wind gusts, then buy reinsurance.


Don't omit possible snow loads and drifts....


Build continuous scaffold at ~2-3 feet lower then new truss plate height, for speedy erection.

Whatever you decide on, practice covering for rain prior to any demo, to see time and #of laborers required to erect rain cover, in a storm front working conditions....

This is the time to call in some favors from friends and competitors for stand by help.

Frame it with rafters, then convert them to trusses under the "new" roof, use wire rope to tie bottom of rafters together till truss chords installed....

really big crane, build new roof on ground, swing into place in one piece.

Get a SE to draw a roof that looks like a truss system, but goes together like a flat roof, then demo old roof line... Scissors trusses? Charge extra for the wide open attic space......
 
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#8 ·
Having done a few bungalow top-ups where we tear off the roof and frame an addition on top - sometimes in a house with a decently-finished basement that we'd like to protect - my approach has shifted over time. Initially I tried tarping over a simple framework that would kind of form a 'tent' over the open structure, but rain inevitably pools on the tarp and gets into the house somehow. My current approach is to buy the biggest ass tarp you can find - one large enough to cover the entire floor in one piece - and just lay it on the floor. (it also helps to leave all the original flooring in place as a tile or wood floor is actually quasi water-resistant). If it doesn't rain torrentially, usually we can shop-vac the water wherever it pools as the first task of the workday.

Fortunately my framer is a total machine and can frame a 2nd floor addition (using a prefab floor and roof truss kit) in about 3-4 days, and I'm usually able to get my roofer in the day after the framer finishes. So the house is exposed to the elements for a week at most.
 
#9 ·
Definitely a fair weather project. I wouldn't try to do it at this time of year personally. As mentioned above, tarping over any sort of framing is tough, the tarp needs to be super tight to avoid any pooling and no area's where wind can get under it or it will wind up ripped in no time. Doing it in sections that are manageable to get sheathed every day is the best option.
 
Discussion starter · #10 ·
Warren said:
Do it in sections. Demo, set trusses, tarp in. Repeat util all is tarped, then start sheathing.

We have also done the truss over method with a pitch increase, using cathedral trusses. End up demoing about 4 foot at the eaves to allow truss insertion.
Click to expand...
So this roof is a complicated roof with multiple valley overlays onto the main roofline. Existing main roofline runs perpendicular to new one, so truss company basically said impossible to make the new main roof an overframe, especially because there would then be multiple new gables and other roofs overarming THAT over frame :eek:

Fouthgeneration said:
Build continuous scaffold at ~2-3 feet lower then new truss plate height, for speedy erection.

really big crane, build new roof on ground, swing into place in one piece.
Click to expand...
I think that is what I am going to do. The main roof is really just a simple gable that has just switched direction and then extends from the existing house over the new addition. I will build it on ground, sheathe and membrane. Lift the bastard up and attach. Then we can do the over frames with the house relatively weathertight
 
Discussion starter · #11 ·
TheConstruct said:
Definitely a fair weather project. I wouldn't try to do it at this time of year personally. As mentioned above, tarping over any sort of framing is tough, the tarp needs to be super tight to avoid any pooling and no area's where wind can get under it or it will wind up ripped in no time. Doing it in sections that are manageable to get sheathed every day is the best option.
Click to expand...
Yeah the weather will most definitely be the issue. Luckily I think I can cut away the existing sheathing and keep the existing trusses largely in tact and tarp it until I get the new roof built on the ground. The existing house is about 25'x40', with the original roof being a simple gable truss system spanning the 25' dimension.

New house will be about 45'x the same 40'. Trusses spanning the 40' dimension with overlays shooting off both sides and all kinds of stuff. I think in total there are 7 gables and a few shed dormers on this one. I will try to upload a few pictures sometime (still getting hang of the forum and need a better way to get pics from phone to computer)
 
#13 ·
I'd also have multiple contingency plans, redundancy to avoid water damage (interior tarps, drainage, vacs, fans and dehumidifiers reserved), and definitely have extra labor. Make sure your insurance will cover you if things still go wrong.
 
#15 ·
Astone said:
3) any other bright ideas?
Click to expand...
Break it down into small(er) demo, frame, sheet sections that can easily and securely be tarped daily or as needed for surprises. The key to that is having an experienced leadman (at a minimum) that can actually make the protection waterproof or resistant enough not to cause damage to existing.

Large enough single tarp to cover the exposed area. Strategic location for seams of multiple tarps, like ridge line as the area grows. Tar paper sheeted roof as you go. Ideally plan the progress to get roofing on in stages to minimized potential water damage. Lots of extra time, expense to do it right.

OR Gamble on large exposed areas against mother nature. Hellva lot more costly if you lose.
 
#16 ·
Do it in the dead of winter..... no liquid water....

I'd stare long and hard at scissors truss that would NOT impinge on the legacy roof, till it was dried in.....

A 12/12 over a 8/12 scissors truss would be ~13'-8" in the center above the top plate, more for E truss? on 40 foot wide , again might come in 2-3 pieces.

This might be the time to get an iron worker and use Steel loading bearing components.....

If the yard is large enough, maybe hire a Utility sub contractor to auger in some telephone poles for the "circus" tent.

Super cheap, rent/buy or lease a exterminator tent to fit the NEW home.......
 
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