Stick Build advice.

[saveasteading]

Thanks you clever lot. Decision made.

 

WE will go for the simple joist hanger solution, with a triangle cut out, or just a horizontal chase. to adapt to the horizontal base

This will not require explanation to the BCO, whereas the traditional timber idea probably would.

The hangers are under £1 each even if branded Strongtie, as compared to £19 with an adjustable bottom.

Everything is held by a myriad of nails, resisting in all directions. the base is, I feel, a temporary support until the nails take the strain.

 

The links from Markocosic are interesting, but they don't resolve this next problem...

 

SE has shown glulam to glulam  connections using very heavy, and rather lovely, brackets as shown below. Unfortunately they are silly money and only come as right angles.

We have hips and valleys converging, which I conveniently ignored on the detail

 

My initial thought was to get nail plates and simply bend them to shape and nail in...but it will need a very small hammer to get into the acute angles.

Then to do the same but with the plates as templates, and make up a heavy bracket on the ground....welding one by one to suit.

 

But it doesn't seem right.

 

The existing (remaining) hip/rafter/ridge connections involve two long twist nails only.

 

Any brilliant ideas?

 

 

[markocosic]

A fabricator would knock those out in no time. Couple of plates. Couple of holes. A weld. No need to try finding them off the shelf?

[Gus Potter]

32 minutes ago, markocosic said:

A fabricator would knock those out in no time. Couple of plates. Couple of holes. A weld. No need to try finding them off the shelf?

If you look at the plate sizes you can see that they are not standard.

 

When designing stuff like this you want to think about minimising cutting. The plate shown is 360 x 260. But what you want to do is to cut the plates out of standard flat bar widths if you can.  Standard widths each side of 260mm are 250mm and 275 mm at 10mm thickness. Now to fabricate this connection the plates need cut at an angle to form the gusset down to the valley. You can get really clever and really reduce the amount of cutting if you don't mind the appearance.

 

For a small order like this you may find a price for the 6mm fillet weld comes in at £30.00 per metre run. Then spray paint it yourself with galv spray... in your own taste of tint / colour.

 

 

 

 

 

 

[saveasteading]

1 hour ago, markocosic said:

A fabricator would knock those out in no time.

Only once he had the pattern, which I think is nigh impossible to predict.

 

The trouble I see though is that the angles are horrible.  Drawn square above, but in reality all on skews.

So I would anticipate tacking the timber up once cut and making a template of tin plate. 

Then lower the beam, fabricate the joints, and then erect. 

And this is one at a time.

Unless there is a welder standing by on site, with something else to occupy his time,  this will add time and cost.

 

BUT, thinks...can they be calculated and premade?  A 45deg roof has a 30??deg hip or valley.

One valley joins into another hip, so the cuts are both......head hurting.

And then there are the site tolerances.

 

Or learn to weld , and  do it in-situ while the joiner waits.

 

This is the one place where appearance may matter, as the rest of the ridge beam will be concealed.. There are 3 more, all different, hidden, at the other end. It is very high though so reasonable tidiness will suffice.

[Miek]

Make some massive hinges out of plate steel welded to some heavy tube stock with a steel rod to suit?That will get round the site tolerance issue. You still have the issue of marking drilling and bolting in the acute angles. 

[saveasteading]

4 hours ago, Miek said:

marking drilling and bolting in the acute angles.

Strongtie have hangers that would work for smaller sections onto a conventionally shaped hip end construction (2 hips coming off the end of a ridge beam). Their detail shows nails being driven in at a slant, so that would be the way with nails or screws. With bolts it should be feasible too, other than right in the corner. Coach bolts won't work.

 

The geometry is pretty horrible, see 3d below.  I have had less complex hip shapes to do in steel, (with the steel all designed by very sophisticated computer) and the only solution was to have sliding cleats to fix by eye and cut at height.. Wood is much more accommodating, but I still think these have to made in situ. 

The hinge idea is interesting...maybe huge ones exist ready-made in some other world (I mean agriculture or sailing or some such.)

[saveasteading]

Question and then an update.

All comments welcomed.

 

The groundworkers have built the block footings with an 8mm error in one area. The joiner was not impressed, and neither am I (laser level used incorrectly).

The joiner arrived with the standard plastic packers expecting 1-3mm undulations, but had to make timber packers..... a tetchy start.

My plan of putting a mastic seal under all the sole plates was ignored on the basis that it was impossible in an 8mm gap.

 

From enquiry it seems that 'nobody' applies any seal under the sole plate. But I wanted to to keep out  draughts and spiders.

I guess we can simply apply a bead along the joint where it is small. 

Question.....What is normal/appropriate where the sole plate is propped 8mm up? Won't it subside and bend, or crush the small packers? But 8mm and diminishing isn't enough to pack with mortar.  

Suggestions please.

 

Progress.

Really impressed with the joiners making cassettes on the ground and lifting to place, so we have 23m x 5m manufactured and erected to eaves in 4 days, including day one being prep and offloading.

 

Glulams will be fixed in place using threaded rod and nuts. Then templates will be made using osb, and then steel copies can be made for bolting in place without holding up the job.

Due to the tight acute angles, and aligning opposite holes in plates,  I am thinking of changing from through bolt to coach screws.

Using standard joist hangers was accepted without demur, so I assume is normal.

 

Some very perceptive advice and suggestions from the joiner.  Where these are more along the lines of 'not how it is done' (despite the Architect and Engineer's designs) I am tending to go his way as it smooths progress, even though I know the design is fine.

 

The day when the walls are in place is a real client pleaser.

[Jenki]

how about thin wedges, use two on top of each other (folding wedge) these are 1-3mm so you will be able to use these, then possibly solid glazing packers. on the diminishing gap. I think 0-3 mm will disappear with weight  / sag / shrinkage anyway

Or Grout (the same used to bed steel columns etc, it will flow, but you will require a moat, and some clean up after.

 

You could use low expanding spray foam to "seal" the larger gaps, then a bead of mastic.   The foam will stop spiders, but not anything that will want to eat it.   

 

https://www.gbplastics.co.uk/Products/Horshoe_frame_wedge_packer_glazing/WP1-3

 

[Roundtuit]

Pack with slate if you're concerned; that's the traditional bodger's packer of choice 😉

[saveasteading]

Slate is the material of choice for us as it is used in the masonry repairs as the final wedge.

I am imagining the house with its many tons of weight sitting on a small timber packer.....which surely will compress?

 

Perhaps we squeeze in whichever packer will fit, starting with the skinny plastic ones, then slate then timber.

[Roundtuit]

2 hours ago, saveasteading said:

Perhaps we squeeze in whichever packer will fit, starting with the skinny plastic ones, then slate then timber.

Why not just use slate, with a bit more slate, and slate on top of that?  Just tap it in until it's tight and chip off anything overhanging.

[Gus Potter]

2 hours ago, saveasteading said:

Slate is the material of choice for us as it is used in the masonry repairs as the final wedge.

I am imagining the house with its many tons of weight sitting on a small timber packer.....which surely will compress?

 

Perhaps we squeeze in whichever packer will fit, starting with the skinny plastic ones, then slate then timber.

The vertical load comes down the studs. Yes, the OSB shed's load but ignore that conservatively.

 

The studs are checked not least for the following load cases:

 

1/Full roof and wall loads plus anything else acting as a downwards load.

2/ Other case which include wind and snow.

 

The main thing here is nearly always load case one. The compressive strength of timber is much more when axaily loaded parallel to the grain. The critical compressive (bearing) check is at the base of the stud. Here you have the stud loaded parallel to the grain bearing on a horizontal wall plate, the grain of the wall / sole plate here is loaded perpendicular to the grain and this has a much lower compressive strength.

 

Conservatively assume that the load goes straight down and does not disperse through the sole plate at 45 deg. Thus if you use a timber packer under the sole plate of the same width as the stud and same length as the width of the sole plate with an equal or greater compressive strength perpendicular to the grain.. that will satisfy the bearing check. If in any doubt get some 50mm (same width as the stud)  wide oak / hard wood and rip that down to make a selection of packers the width of the sole plate. Soak them in preservative after cutting for good measure.

 

Have copied part of a table from the BS below. You can see here how the compressive strength of a timber is much more when loaded parallel to the grain as opposed to perpendicular. You can see for a C16 the compressive strength of the timber loaded axially is 6.8 N/mm^2 and the the sole plate (loaded perpendicular) is 1.7 N/mm^2. Fill in any gaps with something else, maybe add the odd extra packer if you have any doubts about the above and get some extra load spread due to the load sharing properties of the OSB / sole plate / bottom rail of the panel. You may want to do this to spread the load more evenly over the underbuilding if you feel this may be an issue.

 

 

 

For all .. do not use plastic window packers under your timber frame as the are not solid.. they are for windows.. not structural loads. You can buy the right plastic packers for timber frames on line etc.

 

 

 

 

 

 

 

 

[saveasteading]

On 17/06/2022 at 21:56, Roundtuit said:

Why not just use slate, with a bit more slate, and slate on top of that?

Slate is something we have. It is in 3 different thicknesses, but 8mm is the thinnest. 

Therefore we can pack it in where the gap is widest, but not the rest

Thanks for pointing out that not all packers are the same. 

 

The joiner made timber packers by cutting slices off the end of a 5 x 2, so it will be loaded parallel to the grain. 

[Gus Potter]

2 hours ago, saveasteading said:

The joiner made timber packers by cutting slices off the end of a 5 x 2, so it will be loaded parallel to the grain. 

That's fine as the vertical stud (loaded parallel to the grain) applies load to the sole plate. The load the stud appiles to the wall plate is perpendicular to the grain of the sole plate. Thus the packer should have the grain running in the direction from the inside of the wall plate to the outside. If the joiner has just cut a packer off the end of a timber (cross grain) the packer timber grain will be running vertically and just fall apart. Hopefully your joiner has not installed the packers with the grain running vertically.

 

 

[Hobbiniho]

realistically what he should have done is chip down all the rest of the sole plates by 8mm and then tapered the sole plates at the problem area, providong that the rest of the blockwork is level enough this would then have given him a flat level base to work off, timber packers etc is really just a bodge you would really need to use grout to take up a gap that big