Need Roof, Have No Plans

[SansPlans]

Ok. So, let's say you had bought several little house plans (the big enchilada and the 20x30) and then decided to build something else, and kind of somehow without any plans (explaining how is too painful) ended up with a crawlspace poured, and 8"x8"x16" concrete walls all built up, and it's all surface bonded. Looks good to me so far considering its me doing it.

How in the world do I get a roof on this bad boy?  The dimensions are 38'x34', with the roof line running parallel to the 34' walls (slopes down toward the 34' walls).

I wasn't really that worried about it because I had so much other stuff to do before that became an issue, but the time has come.  A few more bags of surface bonding are all that remains.

I haven't put my suspended wood floor in because everything takes me so long I figured it would get all moldy and nasty if I didn't put the roof on first, and then I guess just stick frame in the interior walls.

So I asked my brother who is a building supervisor for a home building company "hey can you just tell me who your framing guys are and I can pay them to put a roof on my house for me rather than me trying to make it happen" and he made it sound like no one would touch it because I have no plans.

So....any ideas?  I'm ready to do this next stage but am a little lost.  How do I go from "concrete wall box" to "concrete wall box with roof."

So my wife contacted this guy who makes trusses and he said they would cost about $2400 dollars for that span and that size of house.  That would be cool, but do I need my interior walls in first so they can help hold the trusses up or do they just span all the way all by themselves?  I was hoping to do the roof then the floor and interior walls even if its more of a pain that way.

[John_C]

The truss guys probably assumed they would have to span the entire building.  Easy enough to call and verify.  You'll need a crane to set those rascals.

You didn't give any info about roof pitch, wind or snow loading, or if you are in an earthquake or hurricane area.  All things the local truss guy would know as well.  If you had all the parameters you could figure what the rafters would be, but given the span they will be large in any case.

I counted 17 courses of block.  Is there a poured tie beam up there?  Anywhere I've been would require one after 16 courses.  If you don't have a tie beam try to design a roof that doesn't put a lot of outward force on those walls.  

Just my opinion and as always YMMV.  Might not be a bad idea to bounce it off an engineer.

[glenn kangiser]

I think John C covered it - trusses usually span the whole thing and don't even want interior supports  - interior walls are non-bearing.  As he said - verify with the truss co - they engineer the trusses but the walls are on you.

[SansPlans]

Hi Guys,
Thanks for your responses!

No there is no tie beam.  Don't trusses by their nature only exert downward force on the walls because of the cross tie thingys? I assumed that just from looking at the way they are designed.  I guess I could do some kind of tie beam, I just got sick of crawling up a ladder with 2 gallon buckets of concrete so I figured that with my Uber Foundation and that its tied into bedrock limestone with rebar that it wouldn't move much from that angle and that the trusses wouldn't cause a enough separating force on the walls.  Maybe I should do that while I still have a chance... hm...  

I thought "eh, I'm going to mortar bolts into the top row and bolt some kind of big pressure treated board thing to it to give me something to nail the trusses to, so won't that kind of hold it together?"

What is YMMV?

Thanks for the info on the no-load-bearing walls. I told me wife that and then she said she remembered him saying that it doesn't need any load bearing walls but that was the first time I had heard that information!

Regarding the slope and snow load, I figured the truss engineer guy would just say "here's what you need". I live in the Texas hill country so while we had tons of ice this year usually there isn't any snow or ice and things like that.

Thanks guys!

[John_C]

In theory, under normal conditions the trusses only exert downward forces.  The 38' wall is a 430 sq ft  sail/billboard; plus the area of the roof itself and the gable ends. High winds can put a lot of pressure on that area.  

Block walls are quite strong in compression, but not particularly strong in other ways. Different codes deal with it by requiring a tie beam and/or vertical columns.  I would poke around and see what has been done in the area.  It may be quite normal for your neck of the woods.  

There are a lot of folks here with much more concrete experience than I have, maybe they will chime in as well.  

[John Raabe]

Yes, trusses should span the entire 34' width and you can specify the pitch. They will be designed for your local loads. You do need something solid to anchor the trusses to - like a PT sill plate with anchor bolts into the concrete (you have that detail in the Enchilada set of plans).

Interior walls can go in later. But, I'm not clear about what is happening with the floor. Have you cast bolts into the wall for a PT ledger to carry a joist floor system? Is the crawlspace vented? Sealed and insulated?

John C has mentioned the issue of racking resistance (wind and earthquake sidewards loads) on the block walls. Surface bonded walls can help with this issue but don't usually eliminate the need for steel, especially in such a long unsupported wall. In the old days, before steel reinforcing, master builders would drop in massive pylons - basically heavy stone or concrete posts to anchor thinner walls at perhaps 12' intervals.

If needed after the fact, you could always consider a flying buttress

[glenn kangiser]

YMMV - your mileage may vary-- meaning --could be different under your circumstances.

A bond beam is a solid poured beam that ties all of those loose blocks together in case of accident or if someone like me were to accidentally bump them while putting up the trusses.  I once bumped a stack of mortared blocks and knocked down about 40 of them.

While surface bonding is great for fast stacking it looks like from this site that solid poured columns and bond beams are still necessary for earthquake bracing.  http://www.drystacked.com/sequence.html

http://www.drystacked.com/windows.html  Shows headers and bond beam with double rebar on top.  The bond beam would give you a place to put your anchor bolts also to tie the roof  trusses on or bolt a wood plate to.

[glenn kangiser]

If you are totally open to the bottom you could put rebar in and solid grout columns into the hollow cells every so often for posts, then bend and lap the rebar into the beam at the top.

[SansPlans]

Yes, trusses should span the entire 34' width and you can specify the pitch. They will be designed for your local loads. You do need something solid to anchor the trusses to - like a PT sill plate with anchor bolts into the concrete (you have that detail in the Enchilada set of plans).

Interior walls can go in later. But, I'm not clear about what is happening with the floor. Have you cast bolts into the wall for a PT ledger to carry a joist floor system? Is the crawlspace vented? Sealed and insulated?

John C has mentioned the issue of racking resistance (wind and earthquake sidewards loads) on the block walls. Surface bonded walls can help with this issue but don't usually eliminate the need for steel, especially in such a long unsupported wall. In the old days, before steel reinforcing, master builders would drop in massive pylons - basically heavy stone or concrete posts to anchor thinner walls at perhaps 12' intervals.

If needed after the fact, you could always consider a flying buttress

Hm...I have a massive beam going down the middle that is 3 2X12's thick bolted/glued together that I was going to put ~17' 2X12's on as a floor joist system.  As far as how to attach to the wall, it will attach to the second row of blocks. I was going to get Pressure Treated board and screw it around the perimeter. I filled every few with concrete up to this level so I was going to screw into it with gozillions of big concrete anchor screws, the kind you have to predrill for. Then I was going to I guess nail the floor joists into that. Then maybe use some construction adhesive to put some little 2x4 supports underneath the board that goes around the perimeter that the joists attach to, and use that to give some more support underneath.  

As far as sealed and insulated, all I have is a big beam going across. In the middle is dirt, weeds, trees... you get the idea.It's in the raw as of now.  I was just going to do the joists/decking thing after it would all be protected from the roof being in place.

As far as venting, I just turned some blocks on their sides at the floor level to provide some holes for ventilation. i thought i could just attach some screen to it to keep rodents out. I was also going to put a fan on them to help pull air through.

I also intend to put down some black plastic before i put the floor in, to keep moisture out.
I attached a picture of the project from quite a bit earlier, but it shows how the inside is right now. Lots of grass, fuzzy forest creatures, and a big beam waiting to have joists attached to it...one day.

I'll have to give some thought to the bond beam. my first thought is, the walls were up for almost a year and this winter endured the worst weather i have ever seen in this part of Texas in the last 15 years, and they were only half surface bonded.  Wind, tornadoes near by, ice, snow, hail, thunderstorms, the works.  I think I would rather do vertical columns with rebar every five or six holes (or whichever holes i can see clear to the bottom) than do a bond beam. Also a bond beam would add undesired height to an already kind of too-tall wall at this point. I know i know I probably should have done one before I got that high.  Also I put on surface bonding uber thick.  If I had to pick I would do vertical columns before I did a bond beam.

Definitely don't want to try flying buttresses, that is a LOT of stonework and I don't have one single vassal much less the multitude of vassals it would take to complete such a job in a timely manner! haha

[SansPlans]

YMMV - your mileage may vary-- meaning --could be different under your circumstances.

A bond beam is a solid poured beam that ties all of those loose blocks together in case of accident or if someone like me were to accidentally bump them while putting up the trusses.  I once bumped a stack of mortared blocks and knocked down about 40 of them.

While surface bonding is great for fast stacking it looks like from this site that solid poured columns and bond beams are still necessary for earthquake bracing.  http://www.drystacked.com/sequence.html

http://www.drystacked.com/windows.html  Shows headers and bond beam with double rebar on top.  The bond beam would give you a place to put your anchor bolts also to tie the roof  trusses on or bolt a wood plate to.

Hm..If it is just for earthquake bracing i think I'll take my chances with the earthquake on the bond beam thing.  I don't think we have earthquakes in this area as far as I am aware.  I'm not sure I have the emotional fortitude to go back and do a bond beam! I've been living in an RV for five months and am going to cry if I don't get a roof on this building soon! Also, I have lots of doors and windows (not on that one wall I sent a picture of, but on the rest of the house) and they have like kind of bond beams where the lintels span across multiple doors and windows, just a few blocks below top level, and it has tons of rebar. My french door even has 1" rebar going all the way across the lintel poured in concrete, tied down the sides poured with concrete and into the foundation which is tied into bedrock with rebar. Most of my doors are done this way, except the other doors have 1/2" rebar across the top instead of the 1" i used in the french door lintel.

I probably will go with vertical columns every few holes.  My brother has a bunch of rebar that he lets me use some of it, so I can do that without having to add more height to the wall which is already kind of too high I think.

As far as anchoring roof to the top, I guess I will put bolts into the holes in which I will have done vertical rebar/concrete and try to tie it in that way.

[SansPlans]

Here's a pic of the kids helping out.

[SansPlans]

Work in progress.

[glenn kangiser]

The vertical columns cemented wouldn't do much without the bond beam.  Some but not much in case of earth quake.  Maybe you don't have that problem down there - Unless you are in an area of subsidence because of oil pumping - that could break it up eventually.  The bond beam could be put in by cutting about 1/2 or 2/3 the way down the blocks in the center and taking it ou with a hammer but I don't know about stopping the holes.  A plumber I knew used to wad up news paper and jamb it in the hole then pour some flowable grout for plugging 4" waste lines.  I think I have see them  put a row of 30 lb felt or something to keep the concrete from going to the bottom but most jobs I am on are filled solid.  I guess you could put felt in the channel made by breaking the centers out.  Doesn't matter to me -- just throwing out ideas in case you want to use them.

Also I see you have a footing inside the wall - could you just put a pt plate and or blocking there to support the ends of your floor joists?  

[glenn kangiser]

If you do the columns and put bolts you could bolt a wood beam there to set your trusses on.  That would tie most of it together after a fashion.  Might even have room to splice the ends of the wood beam together decently.

[glenn kangiser]

Looks like a willing crew -- just a tad on the short side.  Looks like they are learning anyway.

[John_C]

Here is an idea

Use those U blocks open end up on top of your wall.  Leave out the block every 8 to 12 feet where you will run rebar down to the footing.  Lay 2 #4 bars on supports in the U blocks and tie them to the vertical bars.  Use plywood to create a form where you omitted the U blocks and pour the tie beam and vertical columns at the same time.  The upward U creates a form for you to pour the tie beam.

Jump right in here Glenn or John ...  Good idea   ...   Bad idea ??

[glenn kangiser]

Good idea - the only reason I mentioned the cut out way was that he didn't want to raise the wall higher, but yes -- that would do the job.

[MountainDon]

Love your ever so willing to help work crew! Good luck on the roof. Engineered trusses should do fine once you have something to attach them to. I hope to see a roof on it soon with follow up pictures as you work your way thru to living in it.

[SansPlans]

The vertical columns cemented wouldn't do much without the bond beam.  Some but not much in case of earth quake.  Maybe you don't have that problem down there - Unless you are in an area of subsidence because of oil pumping - that could break it up eventually.  The bond beam could be put in by cutting about 1/2 or 2/3 the way down the blocks in the center and taking it ou with a hammer but I don't know about stopping the holes.  A plumber I knew used to wad up news paper and jamb it in the hole then pour some flowable grout for plugging 4" waste lines.  I think I have see them  put a row of 30 lb felt or something to keep the concrete from going to the bottom but most jobs I am on are filled solid.  I guess you could put felt in the channel made by breaking the centers out.  Doesn't matter to me -- just throwing out ideas in case you want to use them.

Also I see you have a footing inside the wall - could you just put a pt plate and or blocking there to support the ends of your floor joists?  

Hm ok I like this idea because it wouldn't require putting another course of blocks up and re-surface bonding the last row.

So I would put a block cutting wheel on my 4" grinder maybe and grind some slots going all the way around and then just knock out the partition segments.  I might be able to cram the partition segments that I cut out in there to help stop the holes, and then maybe add some other stuff in there.

As far as just setting a PT plate on that footing and setting the joists on top of it, sounds like a good idea to me. I was going to screw a plate higher up and match the joists flush with it but it sounds like just setting the plate on the footing  and putting the joists on top would be stronger.  Sounds good to me, thanks for the idea! Even if I had to rip the PT plate to be the right width that would be easier than what I was going to do.  

Ok one last question: on the PT plate I'll be bolting to the very top to give me something to secure the trusses to: How wide/ thick should this be? the blocks are 8" wide, should I just get a 2x8" If thinner, should it be flush to the inside or the outside ledge, or in the middle?

Thanks a lot everyone for your input it is helping a lot!

[John Raabe]

I like John C's suggestion for the bond beam tied into poured columns as the best way to stabilize the wall. You could pour exterior pilasters and tie them to the wall with anchor bolts tied to bars in the pilasters. Lots of work and material there however.

I like Glenn's suggestion of placing the floor bearing on the wide footing but there may not be enough room under the joists and beam (16" min under joists, 12" min under the beam). In that case you could do a PT ledger higher up the wall and then support it with a few bolts AND with PT legs down to bear on the footer. You can insulate the floor joists and screen those block vents and be home free.

For the top plate a PT 2x6 flush with the outside wall would be fine.

[SansPlans]

Thanks for the input guys. I think I am going to go with the bond beam/vertical columns after all. I will cut in though and pour it in the top course rather than add another course just because I don't want to have a big ugly seam going around where I came back and surface bonded the last row after having done the rest.

Next question: After doing some more reading, I think I am going to get myself killed if I have anything to do with getting 38' trusses on my building and  getting them sheathed and secured.

Does anyone have any idea how much this costs to have done? At least truss erection/installing and sheathing?  I can do the metal roofing myself I guess.

Also, who do I get to do that? What are they called, like "truss installation guys" or what?  Will people come do a job that small if its just the roof or do they only want to mess with big jobs? I think i would be better off saving up for having someone else do it but I  am not sure who I am looking for to do the job.

[MountainDon]

If you're having to save up you will have some time to do some local research. You should be able to find a local contractor. For a job that I didn't want to tackle (metal re-roof) we did the usual phone book cold calls and interviews/estimates. We als talked to a local custom builder and got the name of the guys he uses on the homes he builds. We ended up going with them inbetween roofs for the builder. They did a great job from what I can see.

One thing about metal roofs... they are much more slippery to work on than the typical granulated shingle roof. I've never felt too uncomfortable on my roof before the metal went on, but it's more spooky now and it's only a 4:12. But I wouldn't trade the metal for anything else.

[JRR]

I have a neighbor who recently finished a large garage.   It's size and construction reminds me of your project.  A couple of (young) guys did all the truss and roof installation.  I didn't see the effort, but I think they attached temporary "stilts" to each of the trusses and pivoted the whole affair up atop the walls.  As they moved the trusses along the wall, each truss had a temporary counterweighted "leg" hanging down to keep the truss from rolling over.  As soon as a few were located, they did a lot of cross-bracing to make sure a breeze didn't upset everything.

When getting on my metal roof, I use several squares of rubber (interlockable edge) tumble-mats (is that what they are called?) to keep me from slipping too much.

[SansPlans]

Was it close to my house in size? The main thing that is making me wonder if I can do it is the size of the trusses. It seems they would be too heavy to manage without a crane.

[glenn kangiser]

Many truss companies have a crane to deliver the trusses and set them on the roof or know of one available.  You would probably still want some experienced help there as they can be floppy and knock you off if they get away from you.

Having the layout lines an method of fastening and bracing planned, layed out  and marked ahead of time will help.