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pwhit1i
08-04-2009, 09:07 PM
Our house was built in the 1950's in southern Ontario. The house is a bungalow with a side carport. The roof is a rafter based roof and is common between the house and carport. There is no attic separation between the house and carport attic.

Over the carport, there are obvious irregularities alongside the ridge line. Looking inside the attic, some of the rafters have begun to pull away from the ridge board and sag an inch or two. There are no brackets holding the rafters to the ridge board ... they are just toe nailed. They all appear to still be attached but the nail joint has pulled loose. I haven't been over to edge of the attic to see if the root cause is slippage of the lower end of the rafter ... rather than slippage at the top.

Unfortunately, I just had blown in insulation added to the attic, so it is difficult to get around inside the attic.

I have attached a couple of photos that show an exterior view and an attic view. (I have more, but I can only post two photos) In the attic view it is not easy to see the lowered rafters. It is easy to see that there are horozontal boards connecting the rafters over the main part of the house (I don't know the proper term for these connecting beams), but none over the carport. It is also possible to see that there is a support along the lower end of the rafter over the main part of the house (again I don't know the proper term for this), but none over the carport. Inside the attic, there is a drop of a foot or two down to the carport ceiling.

The shingles need to be replaced and I will be contacting roofing companies to deal with the shingles and the rafter issue. I would be interested in any advice on whether I should contact a carpenter/builder rather than a roofer and any advice on what would be considered a reasonable approach to fixing this ... so I have an understanding of things before talking to a roofer/builder.

Any thoughts would be appreciated

Phill

pwhit1i
08-04-2009, 09:08 PM
Here are a couple of more photos

TWhite
08-04-2009, 09:19 PM
If the ridge board has sagged then the bottom beam supporting the rafters must have bowed out away from the carport.

Kgphoto
08-05-2009, 03:05 PM
Did it change or has it always been that way? Probably better get a builder/carpenter or perhaps an engineer to take a look at it for a proper diagnosis.

pwhit1i
08-05-2009, 05:37 PM
The ridge board itself doesn't look like it has sagged. When I have been up on the roof it looks like it is still "true". Over the carport section the ridge board remains "true" but alongside the ridgeboard (particularly on the front-side of the house) the roof sheeting has lowered/sagged in places. Before the blown-in insulation was put in I was able to inspect the join of the rafters to the ridge board and a number of them had sagged at the joint and the nails had pulled partially loose (not all the way out).

We bought the house a couple of years ago from the original family. The home inspector indicated they were still solid but should be dealt with when the shingles were ready to be replaced ... which would be in a couple of years (meaning now)

The original family said they remember it being that way for a long time. They indicated that when they had the roof done 15 years before we bought that the issue was there then.

A W Smith
08-05-2009, 06:49 PM
which way do the ceiling joists run in the carport? side to side? or front to back?
Could be there's nothing to restrain the thrust of the rafters besides the collar ties. Is there a corresponding bow outward at the facia/gutter? You would think a thrust problem would pull the ridge down as well but that's not always the case.

always-learning
08-05-2009, 08:29 PM
which way do the ceiling joists run in the carport? side to side? or front to back?
Could be there's nothing to restrain the thrust of the rafters besides the collar ties. Is there a corresponding bow outward at the facia/gutter? You would think a thrust problem would pull the ridge down as well but that's not always the case.

Agreed with your deduction..... although I would have to ask you.......


What collar ties?


The end gable wall rafter isn't sagged because it's supported from below. He could take a stringline or laser and see if it's bowed if he really wanted to, although I don't see the point of doing so. If anything, a few collar ties could be added to stop or limit further movement.

A W Smith
08-05-2009, 08:34 PM
Agreed with your deduction..... although I would have to ask you.......


What collar ties?


The end gable wall rafter isn't sagged because it's supported from below. He could take a stringline or laser and see if it's bowed if he really wanted to, although I don't see the point of doing so. If anything, a few collar ties could be added to stop or limit further movement. I bet the ceiling joists are perpendicular to the outside wall of the home and not parallel. What would be supporting them, if they were ?

oh you're right. no collar ties. i was looking at this photo
http://forums.jlconline.com/forums/attachment.php?attachmentid=15625&d=1249437774


when i should have looked at this photo
http://forums.jlconline.com/forums/attachment.php?attachmentid=15628&d=1249438092

Greg From K/W
08-07-2009, 10:16 AM
The support posts in the middle of the ridge would prevent it from sagging. If there is no sway to the trough inward on the side of the ridge where the rafters have moved, then would it not be the case that the rafters have been cut a little short on that side if only the rafters have pulled or fallen away? If this is the case you could jack them up flush at the top and add lumber under them all to help support them. After that add collar ties to each rafter. But I would definitely get a carpenter to look at it and or an engineer. Don't hire a joe blow handy man. Make sure that you get a carpenter for this.

dave_k
08-07-2009, 02:43 PM
Just out of curiosity are your exterior walls bowed out a little? Are you located in a snow belt off? I agree that the roof should have had collar ties. I would say the ceiling joists weren't nailed properly either. It wouldn't be difficult to stabilize the situation. Fixing it in an occupied house would be very difficult. If you PM me the span of the roof and your location (for snow load info) I could tell you what the OBC currently requires if you decide to repair it.

pwhit1i
08-07-2009, 08:45 PM
I want to thank everyone for their replies and input on this.

In terms of a few of the questions that have been asked:

- Direction of the ceiling joists over the carport -> I'm not sure. I did look once when I was in the attic, but I don't recall if they are side to side or front to back. The carport joists were lower than the ceiling joists for the house it self

- Collar ties -> It is very curious why there were no collar ties installed over the carport. They are installed for the rafters over the house itself, but even though the attic is common with the house, they stop right at the boundary of the house wall.

- Bowing of the outside walls/eves -> there doesn't appear to be any bowing of the walls (none of the rafters have dropped over the house itself ... all of them are over the carport). Having said that, I haven't looked closely ... since the rafters that have dropped have only dropped an inch or two, it would likely be tough to see an appreciable bow in the eves over the carport.

- Roof span & snow load - I am out of town so I can't measure the span at the moment. In terms of snow load, we are not in a particularly heavy snow area. We are east of Toronto fairly close to lake ontario.


In terms of some additional questions I have:
- Collar ties -> is it the norm to extend the collar ties to the rafters over the carport ... or is it typical to stop them at the edge of the house and not have them over the carport?

- In one of the photos that shows the side of the attic, there is partial wall/frame supporting the rafters over the outside walls of the house itself, but this wall/frame stops at the edge of the house and doesn't continue over the carport. What is this wall/frame called? Should it have continued over the carport to help support the roof load over the carport? I assume since there is no load bearing wall in the carport if it should have gone across the carport, then this wall/frame should have spanned the carport width and transfered the load to both the house itself and the front post of the carport.

- Is this a job that would be best done from above with the roof sheeting off (ie. when we are getting the roof re-shingled) or is it something that could/should be done from inside the attic (obviously before the roof is re-shingled)? From the underside, the sheeting doesn't look to be in bad shape. I was thinking that it would likely be easier to pull the rafters up and re-nail them properly if the roof sheeting was off ... rather than trying to jack them up from below with the weight of the roof sheeting and shingles.

Thanks again for all your input.

Phill

Kent Brobeck
08-07-2009, 09:22 PM
Phil, Did you blow insulation over the carport? If yes did it sag after you blew in the insulation. By the looks of the photo it is insulated above the carport. By the direction of the soffit the ceiling joist are running front to back. If you did insulate above the carport the weight of the celulose is pulling the ridge down and causing the roof to sage. One thing about celulose is it will take on any surrounding moisture and you would get plenty from the car port. This will cause the weight of the celulose to increase.

There is no reason to insulate above the carport since this is unheated space below. What you would want to do would be to frame a rake wall at the end of your house where the carport starts and the heated part of the house stops. Cover it with osb and house wrap to give you a moisture break from the carport.

To correct the problem you would need to attach probably two come alongs to both the front and back of the carport and crank them down. After the preasure is max pound up on the ridge and the rafters with a 10 lb sledge and it will go back in place.

This all assumes you insulated above the carport?

Kent Brobeck
08-07-2009, 09:34 PM
Phil, it just dawned on me that I doubt you are a professional. Take the info you got an exit.
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pwhit1i
08-14-2009, 06:59 AM
You are right. I am not associated with the construction industry.

Thanks to everyone for their input. It was helpful.

Phill

Top Notch
08-14-2009, 03:57 PM
As I looked in the photo of the ridge I think I saw a couple of rafters seated lower than the ridge beam itself. That leads me to believe the person who framed the roof came up short in that area and just nailed them where they fit rather than shim or cut new ones. A 2x6 rafter not fully bearing on the ridge would be reduced to a 2x4 and then sag under stress os snow.