Roof Supports

[imported_gbeichho]

OK, I have a weird situation in my cottage attic. It has a wide variety of roof supports (ceiling joists, collar ties, odd-looking truss).
It has metal roofing and a very low slope (50/130"). This is in Canada in a high snow area. I think the rafters might be bowing very slightly, but overall the roof appears fine. I am about to close off the ceiling (right now it is a drop ceiling so I have easy access to the attic area) so I was wondering if I should beef it up before losing access to it.

Any thoughts?

Thanks,

George

I have included an approximate drawing. The three trusses appear to take the majority of the load.

http://members.rogers.com/kge/RoofPlan16.bmp

[Wgoodrich]

Are these pre-engineered trusses or home made trusses? What is the distance between trusses and what type of sheething that supports the roof. Are the sheathing 2x4s on edge spanning between trusses? If this is a true engineered truss and say 4' between trusses and 2x4 on edge sheathing spaning to support the roof you should be fine for a 20 pound snow load in our area about mid USA. For the type snow load I estimate you to have you may need to beef up the 2x4 on edge sheathing spans if that is what you have. Too much unknown to help a lot with what you have provided in facts.

Curious

Wg

[imported_gbeichho]

Very curious indeed... I took some pictures, but here are a few facts first.

Rafters 2x4
Ceiling Joists 2x4
Home made truss beam 2x6
Home made truss trellis 2x4
Collar ties 2x4

Now the pictures: First three are of the truss
Note it does not go all the way out to the outside wall on the left...

http://www.eichholzer.net/webpostings/TrussLeft8x6.jpg

Note the collar ties down the line here...

http://www.eichholzer.net/webpostings/TrussMiddle8x6.jpg

Note minimal ceiling joists to hold drop ceiling here...

http://www.eichholzer.net/webpostings/TrussRight8x6.jpg

Again, more pictures of oddly placed ceiling joists (not even attached to rafter)

http://www.eichholzer.net/webpostings/MoreAttic8x6.JPG

Note more regular (every 2 rafters) ceiling joists to hold insulation and drywall ceiling:

http://www.eichholzer.net/webpostings/Insulated8x6.JPG

Here is a stronger tie to support a ceiling fan

http://www.eichholzer.net/webpostings/CeilingFan8x6.JPG

We'll just ignore all of the bad wiring runs... I know how to fix those.

[Wgoodrich]

I would say the 2x4 rafters were bowing inviting the beefing up truss attempts. It looks like the stiff legs have been added to create a truss look alike to try to beef up the rafters concerning snow loading.

The odd spacing of ceiling joists do not meet sizing required per Code You can't even use the repetitive spacing to size the ceiling joists per Code because you have no common spacing between joists.

The larger ceiling joists looks again like they have been added to help beef up inadequate 2x4 ceiling joists that were originally installed and probably showing bowing due to weight of roof and ceiling material.

I would look at the truss like bracing holding up the roof and see if they are supported by a bearing wall supported on piers under the floor against the ground. This would give you some peace of mind.

The braces nailed on the side of the ceiling joists holding up the rafters are not a good way to secure those braces. They should be sitting on the ceiling joists not nailed to the side of the joists.

It concerns me what looks like a home made metal chimney. I would look closely at that. I suspect you should buy triple liner flue piping to ensure against fire due to heat transfer if this is a wood type fire place or stove. This chimney if that is what I am seeing concerns me for your safety.

Hope this helps

Wg

[imported_gbeichho]

Ahhh, good call on the chimney. It was decommisioned as soon as we bought the place. Our WET inspector noted it right away. We had him put in a much newer, nicer, and better located stove with a proper chimney. I think I'll turn it into a roof vent soon.

(I think that old stove caused some of the floor bowing we're seeing too. It was one of the old cast iron ones)

As you can tell from my other thread, the load bearing wall is NOT supported by piers (offset by 18"... dumb weekend warriors). I think I have to fix the supports on the bottom first (the sinking wall which is not really supporting the roof in this scenario), and put a beam under the load bearing wall.

As for those braces nailed to the side of the joists, I actually think they're there to hold the Joists up (not the rafters) in that spot because that's where they put a ceiling fan.

Do you think it's worth putting proper ceiling joists? I'm planning to put in a ceiling, and I'll be the contractor is just going to use strapping. Once it's up, it will be a lot harder to put in proper joists.
What size joists should they be, and how often? (every rafter???)

Thanks for all your input.

[Wgoodrich]

Floor joists under a bearing wall may be offset but only a limited distance. If that distance is exceeded then a pier must be constructed under that floor joist with a footing at least 12" below undisturbed dirt and at least below the designated frost line for your geographic location. See the copied rule below.

COPIED SECTION OF IRC 2000;

R502.4 Joists under bearing partitions. Joists under parallel
bearing partitions shall be of adequate size to support the load.
Double joists, sized to adequately support the load, that are sep-
arated to permit the installation of piping or vents shall be full
depth solid blockedwith lumber not less than 2 inches (51 mm)
in nominal thickness spaced not more than 4 feet (1219 mm)on
center. Bearing partitions perpendicular to joists shall not be
offset from supporting girders,walls or partitionsmore than the
joist depth unless such joists are of sufficient size to carry the
additional load.



The floor joists ends must be supported at their ends. This is true only if this floor joist is not overlong and that part not supporting anything because of a sister joist doing the supporting is doing the supporting. What I am saying is that I have often found floor joists that should have been cut off at the header, girder etc. that supports that floor joist yet the extra long floor joists were installed with the extra length left on just hanging there doing nothing. Check to see if these ends of joists are actually doing anything toward supporting the structure or just never got cut off as they should have been.

See the following COPIED SECTION OF THE IRC 2000;

R502.6 Bearing. The ends of each joist, beam or girder shall
have not less than 1.5 inches (38 mm) of bearing on wood or
metal and not less than 3 inches (76 mm) on masonry or con-
crete except where supported on a 1-inch-by-4-inch (25.4 mm
by 102mm)ribbon strip and nailed to the adjacent stud or by the
use of approved joist hangers.


I am glad you corrected your chimney. You might use that duct as an outlet for a whole house fan effectively closing off that duct in the winter. May help in your comfort zone inside you house in the summer creating a large air flow exhausted out the roof when hot. Just an idea. Otherwise if no use remove it.

Did you take a level and find if the older outside footing side of the house has a descending floor level? Then find the side of the house with the new outside footing to be with a level floor? This should tell you a lot as to what you have a sinking footer or a rising ground support such as a rock working out of the ground.

If you are going to install a ceiling to the joists then the repetitive span should not exceed 16" with 1/2 ceiling. Now is the time to put proper size and repetitive span joists in after you remove your suspended ceiling and before you install your new ceiling.

To size your ceiling joist or floor joists or girders I need confirmation you are using SPF lumber and the length of the joists and if floor joists used for living area or bedroom area. Then I need to know the longest distance between the repetitive spanning joists floor or ceiling.

Just some ideas

Wg

[imported_gbeichho]

If you are going to install a ceiling to the joists then the repetitive span should not exceed 16" with 1/2 ceiling. Now is the time to put proper size and repetitive span joists in after you remove your suspended ceiling and before you install your new ceiling.

Yes, I thought so... If I put 2x6 joists on the drop ceiling side (11.5' span to the load bearing wall), how should I nail them? Do I have to run another ceiling joist from the wall to the opposite side as well (this might be hard because you can see it already has a ceiling and 2x4 joists every 32" with insulation). Or should I forget about supporting the roof and just use the joists to support the new ceiling?

Did you take a level and find if the older outside footing side of the house has a descending floor level? Then find the side of the house with the new outside footing to be with a level floor? This should tell you a lot as to what you have a sinking footer or a rising ground support such as a rock working out of the ground.

Yes, I'll leave that discussion to the other thread...

I am glad you corrected your chimney. You might use that duct as an outlet for a whole house fan effectively closing off that duct in the winter. May help in your comfort zone inside you house in the summer creating a large air flow exhausted out the roof when hot. Just an idea. Otherwise if no use remove it.

Can I run some ducting over to a stove hood (we don't have one yet) or should I just vent a stove directly through the wall and leave this one as a whole house vent or attic vent? I would like to use this somehow because it's so nicely integrated into my metal roof, and removing it from the roof itself would be a big hassle...

This cottage is rarely used in the winter (for now), as the water system is not winterized. It is a shame some of it is so poorly constructed because the roof is top notch metal, and the siding is high quality metal siding... very long term, low maintenance. Just foundation and shoddy ceiling problems. Ironic.

[Wgoodrich]

The range hood should be a ventless or vented out the side as short as possible. Remember to install a damper that closes to keep critters out when you are not there.

The vent going through the roof may stay but winter use and summer use need to be handled differently and can be done easily if thought ahead.

Whole house fan would help a lot in summer. There should be a removable rubber sleave connecting the whole house fan to that vent. Then in winter time remove that rubber boot and install a cap that will block off any heat loss.

Just some ideas

Wg

[imported_gbeichho]

Thanks for all the advice.

I just looked up whole house fan, now I understand what it is. We probably wouldn't put it in that room because of the look (we're putting up a nice ceiling there). But I'm going to try to keep the roof vent maybe put a wind powered turbine on it, then I would consider a whole house fan in a nearby room (ugly ceiling area in kitchen...).

Also, when I add the proper ceiling joists, should I fasten them to the rafters and/or load bearing wall, or just use them to hold the vertical load of the ceiling?

[Wgoodrich]

Stiff legs installed to hold up the roof to shorten span or just to add support must be installed no more than a 45 degree angle and mounted to the rafter then sitting on a top plate of a supporting wall that has a foundation or pier under that supporting wall. Ceiling joist span charts are size only to hold the ceiling sheathing [aka normally drywall] or if using the second span chart for ceiling joist then only supporting LIMITED storage in that attic.

If a ceiling joist is sized to support a floor with a 40 pound load in your locality then the ceiling joist may support a stiff leg but only if that ceiling joist is sized the the spanning charts for floor joists desisgned to carry the load. In my area the snow load is only 20 pound a bedroom floor joist is designed to carry a 30 pound live load and a 10 or 20 pound dead load, If the ceiling joist in my area is sized as a floor joist then yes a stiff leg may be installed using the floor joist sized ceiling joist spanning to support the roof. If I remember right your area calls for a 40 pound snow load that would require you to size your ceiling joists as a living area of 40 pound live load or 20 pound dead load to use a stiff leg to support your roof supported from the ceiling joists.

I advise installing you stiff legs to support your rafters no more than a 45 degree from vertacle supported on a load bearing wall sitting on a foundation or pier supported from the earth below.

The ceiling joists may be dove tailed to lay on your supporting wall top plate on outside perimeter of your home or you may use joist hanger brackets and support the ceiling joists in a baloon framing technique design mounting to the side of the top plate using the ceiling joist hanger brackets to support the joist to the wall. Just toe nailing to the side of hte top plate does not meet Code requirements.

Hope this helps

Wg