I’m working on a project where we need to cut an opening and install a man-door in a concrete block wall.
We have a likely masonry guy who can help us with the opening but I’d like some clues on the process.
What’s proper work sequence here? 8″ block, 1 story, bearing wall, opening for std 3-0x6-8 entry door.
What material should be used for the header?
Should 2x treated material be used for ‘bucks’ for the inside of the RO?
What? What? What?
Thank you,
Pat
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Check the applicable building code for your area. There are tables for the size and composition of lintels in a load-bearing block wall. It depends on how many stories it's supporting, and a few other things.
I would use either standard framing lumber or a steel beam for the lintel, depending on whether a properly sized wood lintel would fit in the space available above the RO. Standard framing lumber is good for the jacks unless the code specifies rot-resistant material in which case I'd suggest using hemlock.
I would definitely not use PT, especially in conjunction with a steel lintel.
Dinosaur
How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....
Never saw a wooden header in a masonry wall. Seems like it defeats the purpose.
MikeInsert initially amusing but ultimately annoying catch phrase here.
I have seen a couple over the years, but they're humongous big basterds. You couldn't fit one in above a standard doorway unless your block wall was at least 9 feet.
I prefer steel. The discussion about what kind of wood to use was about the jacks, not the lintel.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
How can a wood lintel support a block wall. The wood shrinks and the block doesn't.
It would all be academic in a place with a wind code anyway since uplift is as important as download.
Why not do it the normal way either a double steel angle or lintel blocks with rebar grouted in? Any mason would be able to do this for a door opening.
Just out of curiosity, how does a steel lintel counter wind uplift better than a lintel made of something else?
As far as wood lintels in masonry walls, like I've said I've seen a few, but they were old and the wall was built that way. They were also massive. I would not try to insert a wood lintel into an existing block wall.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
Wood doesn't shrink lengthwise. Only in width.. If you're putting in a wood lintel You adjust for it's potential shrinkage depending on how green it is.. As for sizing, that depends on the load above. Most of the places I've seen wood lintels there is no real load.
I realize that may be difficult to understand if all you've ever built are stick framed homes but it's pretty common in timberframed homes..
As for the myth that wood and masonary don't mix.. with proper attention to details it is no problem. If you look at European timberframes that have been around for as much as a thousand years it works fine..
And as for up lift resistance Look to anchor bolt spacing for your solution..
If the wood shrinks in width, that 2x8 is not a 2x8 anymore and the height of the lentil is smaller
If it's green it will shrink.. If it's dried down to about 15% moisture content it won't shrink appreciably from that (depending on where you live) If you are in the arrid west It's probably better to dry it down to about 5% moisture.. Actually it will do so itself as it goes through the heating cycle.
There are charts around (sorry I've got mine all packed up in the attic that's sealed for the winter so I can't look it up for you) but do the calculations and simply add the required amount to the opening. As the wood dries fill the gap with chaulk and then when you put the trim on the wood you'll cover up any gap..
Off the top of my head depending on the species of wood, it's thickness, and how green it is when you get it. I'd say 3/16ths should be about enough. Of course if your load calculations require something other than a 2 inch thick piece (which I strongly believe would be required in most cases) you'd have to adjust accordingly.
IT's not hard to do, simply requires a referance chart and some basic math..
I did all the calculations myself for my place and now years later through many heating seasons everything came out really nice.. (and that was my first experiance with wood shrinkage).. I bought everything green and rough sawn directly from the mill.
I would find a local sawmill to saw you the required pieces out of white oak.. Not hemlock.. My book says that hemlock doesn't have any rot resistance. Perhaps he was thinking of Tamarck?
White oak is selling for .80 cents per bd/ft. rough and green at the sawmill. You can use Green because wood doesn't shrink in length when green only in width..
Simply remember not to use regular nails stainless steel, brass, silicone bronze, or heavy galvanized.. Normal nails will be decayed by the tannins in white oak and the resultant acids will cause rot in the wood around the nails..
Been through this before; I meant hemlock. It's called 'Pruche' in French. I forget the Latin genus and specie designation.
It does not rot easily. Your book must be talking about something else. I have hemlock posts that have been sitting in the lake supporting a dock for 16+ years. They have outlasted the spruce decking and some of the framing and are as solid as the day I put them in.
We use hemlock for building raised garden beds and retaining walls all the time. Haven't had one rot out or even come close in the 20 years I've been doing this.
In this province, virtually all commercially available non-PT posts larger than 4x4 are hemlock. If it rotted easily, every deck and porch roof in the province would have fallen down long since.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
Must be a Canadian thing.. <big Grin> What we call hemlock around here is well known for it's propensity to rot..It's also not known for it's size.
However Tamarack is very common both around here and further up north. Tamarack is a weird tree in that it's coniferous but sheds it's needles every fall like a deciduous tree. It is fairly decay resistant as well. plus some grows to be reasonably decent in size.. A lot of the flooring in my home is tamarack because it's so modestly priced..
Might be but I don't have any way of knowing.
These trees are among the largest that grow here; I just had one that died taken down--70 feet tall, almost 30" at the butt, and only about 40 years old. (It died because we moved the house and cut a bunch of its roots excavating for the new foundation. Took 9 years to die after that, too. Tough trees....)
They are conifers with very short needles and tiny seed cones--about an inch or less in max dimension. Wood when dry is pale cream or off white; coarse and straight grained. They grow very tall very quickly and do not have a lot of lower branches so for a mature tree you can easily get 30-36 feet of clear lumber.
Knots, where there are any, do not bleed sap.
It's a structurally rated species and spans for hemlock are given in all the standard NBC tables.
Most mills cut large square posts from it and slice the outside into 1" 'barn-board' stock that is not KDed or planed and are sold very cheaply. To give you an idea, 5/4x6 spruce decking (when you can get it) is over $12 for a 16 footer. A hemlock 1x6x16 (unplaned) sells for $2.
Okay, I had a couple of minutes so I looked for it on the web.
Latin name: Tsuga canadensisEnglish name: Eastern hemlockFrench name: Pruche du Canada
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Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
Sure doesn't sound like tamarck, since you didn't mention shedding needles every fall.
I know it's not like the hemlock around here because that is never of any size. So I must admit I'm not familar with it..
The very first thing to do is to cut a slot at the top of the opening, extending for some length past the opening. Then structural steel is put into the slot, immediately. Indeed, the slot is usually made on one side, steel inserted, then the slot is made on the other side, and the steel pushed through - that way, the section is never left completely without support.
You mason will know the correct details - the size and type of steel, etc.
With the steel in place, the door frame only fills the opening; the weight is borne by the steel.
Not sure of your local but here in FL the masonry wall would have to have a precast lintel or box lintel to support the wall above. Wood cannot be used to suppport masonry.
Check into a Powers Lintel. They are great. Easy to lift and install and then fill with concrete and you are good to go!
Mike
If you are in Florida that will be a bond beam or a tie beam anyway. If there are no doweled cells in your proposed opening you just cut it out but you would still need to pour the edges of the door frame solid with a #5 in it.
My inspector allowed me to "stick and dowel" that on top and bottom although it is not strictly code conforming. We then formed and poured up as we went with the concrete. I set 3/4" plywood on the inside and outside walls with tapcons, ending at the MO for the door with 1x2 cleats on the edge.
Measure, measure and measure again for size and plumb. I cheated and made a MO sized "door" out of plywood (minus the thickness of the form) with handles on it as a guide and sanity check.
That also covered the hole at night to keep the critters out.
Then we started putting face boards on this form as we poured it solid, ending up with a 4-5" hole at the top that we packed with mud and covered. One more test with the pattern door and it's miller time.
When we took the form down we had a perfect door opening.
Edited 11/3/2009 11:28 am ET by gfretwell