Half block half stick wall?

[River Runner]

Any thoughts about the structural implications of building a wall that is half CMU block and the upper half stick built?

I know that you can’t obviously stack two stick framed sections on each other because your creating a hinge. Would this be the same with a reinforced block wall?

My initial thought is that it shouldn’t matter because we stick frame on the top of a block stem wall but that’s only a foot or so above grade.

 

[finn]

Walkout basement on both my house and the neighbor’s is like that.

Don’t know about mine, but they put rebar in the cores of his, then filled the cores. Not all, but several, especially near the corner

 

[matt_i]

I'd say completely viable with proper prep. As with above, you don't want to have the top row of blocks crack away from the rest with the wood stuck to it. A block wall is easy to throw together but harder to get the strength approaching that of a poured wall. Rebar, both perimeter and vertical, plus core-filling with grout are your friends. I'm not sure if its below grade but waterproofing would be the other focus. I think most people find it easier and cheaper to build the wooden section hence the lower height of cementious materials. However, with a stake in the present-day material supply and costs, that might not be the case.

 

[NUTTSGT]

I'd have no issue doing that but I would take a few precautions. Personally, I'd core fill alot of those blocks, by hand, my time, my dime.

You're also in Idaho, do you heat this space ? That block wall is going to make it harder to heat the space. It will transfer that cold inside and heat out. Be prepared to insulate it and how will you accomplish that ?

 

[Retroman]

They frame two story homes with wood. Frame the bottom floor sheet the top of the framing for the second floor then frame the second floor walls. I don't think the "Hinge" you refer to would be an issue with some shear panels connecting the two framing sections.

 

[Bert_]

They frame two story homes with wood. Frame the bottom floor sheet the top of the framing for the second floor then frame the second floor walls. I don't think the "Hinge" you refer to would be an issue with some shear panels connecting the two framing sections.

In a house that is called platform framing. It only works because there is a floor at the joint.

 

[River Runner]

Sorry I didn’t give specific details, I was mostly looking for thoughts on the concept. Building is permitted Agricultural but will be used for shop space also so yes it will be heated, mostly by wood.

Current foundation is 4’ high solid filled block stem wall with a bond beam and bar, footings are 2-4’ deep dependent on which side of building.

I originally was going to stick frame on top but block is considerably cheaper at the moment and my father in law was a mason so we opted to just keep going up with block. Also I really like the idea of block walls on the inside of the shop.

We are currently about 6’ up with block and it’s a big building, 40x64x12 . We can get about 300 block laid a day but that will slow down as we get higher. We are laying vertical bar every 4’ and will fill those cells.

we are getting close to the point that we will do another bond beam course and lay horizontal bar and the thought crossed my mind, that maybe setting an 8’ framed wall on top would save a lot of time I’d even get a little taller ceiling.

I planned on running 2 layers of 2” foam on the outside of the block and if the upper section of wall was framed I’d just keep it going to the top with it.

We can definitely just keep going with the block , but I like exploring options.

 

[NUTTSGT]

Two layers of 2" foam on the outside, what is the plan to cover that foam ?

 

[River Runner]

Metal siding over foam.
First layer of foam, then furring strips ran over foam, then second layer of foam between furring strips, metal screwed to furring strips.

 

[River Runner]

Foam below grade and up 6” given a parge coat like tuff stuff

 

[NUTTSGT]

Furring strips or

Metal siding over foam.
First layer of foam, then furring strips ran over foam, then second layer of foam between furring strips, metal screwed to furring strips.

I hope that works for you. I don't think I would do that. It doesn't sound like there will be enough to hold the metal on. I'd be afraid of it coming off in high winds if the can get underneath it.

However, what you are describing and what I am imagining could be two totally different things.

 

[WNYflyer]

Any thoughts about the structural implications of building a wall that is half CMU block and the upper half stick built?

I know that you can’t obviously stack two stick framed sections on each other because your creating a hinge. Would this be the same with a reinforced block wall?

My initial thought is that it shouldn’t matter because we stick frame on the top of a block stem wall but that’s only a foot or so above grade.

Yes in your described case the location where the dissimilar materials/construction of CMU and wood framing meet would also be a "hinge" location that is laterally unsupported/restrained. Theoretically I suppose the lower CMU could be designed as a retaining wall type structure with appropriate foundation to provide the required lateral support of the joint but seeing that you are dealing with some existing construction that does not look like an option, not to mention the geometry/heights you seem to talking about.

How high was the existing filled CMU foundation wall relative to both the lowest exterior grade and anticipated finish floor elevation?

 

[River Runner]

I will backfill and bring the grade to the same level around the filled stem wall. This puts the top of the first bond beam course at 12” above the concrete floor. The exterior grade will be about 6” below that.

I thought if I did 8’ of block above the first bond beam with the last course being the second bond beam I could perhaps place a 4’ wall on top, maximizing lumber material efficiency. I’d end up with a 13’ ceiling height from concrete floor.

I even thought I could place threaded rod into the filled cores going up into the top plate of the 4’ framed wall and tighten it down with a nut to really secure the framed wall on top….but perhaps I’m overly complicating things at that point and should just lay another 4’.

 

[kbs2244]

Do any of what you described as a wall, but
use "J" bolts in the cores of the top row of block to tie the stick built wall to the block.
If you go all the way to the eves with bock, "J" bolt a header on top of the last row as something to fasten the rafters to.

 

[KpFlyz]

I am currently building a 28 x 42 building in eastern TN.

Building has 2 foot by 2 foot footers with 2 rows of rebar. Back wall is 12 inch block, 8 foot high and 1 foot above grade. The block side walls go from 8 foot down to 3 foot to stay above grade. The walls are filled with concrete and have rebar every other cell. I waterproof exterior of walls, installed drain tile, and put one inch 4x8 foam sheets to insulate and protect waterproofing from backfill. Everyone I spoke to around my area suggested I backfill 5 feet up with 3/4 rock.

Walls are framed the rest of the way to give me an interior wall height of 12 ft 6.

I should have the building completed in another 30 days. I would definitely build it this way again if I had to do it again.

 

[WNYflyer]

I will backfill and bring the grade to the same level around the filled stem wall. This puts the top of the first bond beam course at 12” above the concrete floor. The exterior grade will be about 6” below that.

I thought if I did 8’ of block above the first bond beam with the last course being the second bond beam I could perhaps place a 4’ wall on top, maximizing lumber material efficiency. I’d end up with a 13’ ceiling height from concrete floor.

I even thought I could place threaded rod into the filled cores going up into the top plate of the 4’ framed wall and tighten it down with a nut to really secure the framed wall on top….but perhaps I’m overly complicating things at that point and should just lay another 4’.

As noted before the joint where the wood framed wall and CMU meet would be an unstable hinge joint that would need to laterally supported by some type of structural system . Most 1-story CMU buildings would have the CMU designed to span as a beam continuously vertically between the points of typical lateral supports which would typically be the foundation and roof diaphragm. Just go all the way to the roof with CMU and look at the code for some suggested roof/CMU connections.

Your local residential building code would have quite a bit of prescriptive design information for CMU in section R606. A lot of requirements are based on the structures "Seismic Design Category" which takes into account the structure location's seismic activity, type of construction, building use, etc. Looks like for prescriptive design residential code the building authority would be required to establish the structures "Seismic Design Category". Particular care would be taken for requirements in the vicinity of openings, corners of walls, foundation and roof locations. Of course need to be worried about the amount of shear walls, vertical steel reinforcing embedment's and laps splices and also the requirements for vertical control joints and there suggested locations.

Attached is a link to the Idaho Residential building code which may be of some use/guidance to you though it sounds like you are pretty far down the road construction wise already.

https://up.codes/viewer/idaho/irc-2018/chapter/6/wall-construction#6