5mm over 5 metres sole plate level

[jack1962]

What is an acceptable tolerance when putting down a sole plate? when to pack and not to pack?

 

[markc]

Pack wherever the plate could/would deform under load. I.E under bearing / connection points, 

[Mr Punter]

I have had some that are out by 20mm.  Solid packing under studs and grout from a mortar gun between packers.  Make sure the packing is either all under or all on top the DPC.  It is a pain if it is mixed.  The structural grout goes off surprisingly well, even if it is a bit messy.

[Gus Potter]

4 hours ago, jack1962 said:

What is an acceptable tolerance when putting down a sole plate? when to pack and not to pack?

 

Hi Jack1962.

 

As a general rule of thumb. Mortar bedding should be between 5 and 20mm thick. Less than 5mm and the bed is too thin, more than 20mm and the mortar will start to crack, shrink, loose strength as it's too thick.

 

Sole plates need to be evenly bedded so you can see that at less than 5mm thick they will also be hard to gently tamp down to level (like bedding a brick), more than 20mm and the mortar will start to just spill out of the bed. The mortar will tend to be less compacted at the edges and more in the middle so the sole plate will want to twist (rock) one way or the other. Also, once you exceed 20mm of mortar you can impact on the performance of any fixings holding down the sole plate.

 

The other thing to look out for is how much the sole plate is overhanging say masonry below. Generally for a 90 -100mm wide sole plate you want it over / underhanging by no more than 12mm. For a 140 - 150mm sole plate no more than 20mm. If you exceed this then a number of issues arise.

 

The first is that the sole plate can load the supporting structure below (say masonry) eccentrically (usually not about it's centre of gravity) and this can introduce unwanted bending type forces, local over stressing in the masonry for example. Again you can have an issue with the fixings as if the timber is too far overhanging the fixings can end up too close to the edge of the timber / masonry / concrete and thus become less effective.

 

If your masonry is well off being flat (level along the top) then if you get really stuck you can use an extra sole plate that is fixed to the masonry on some bedding to partly sweeten it out. Then put another sole plate on top which is packed with structural packers. Each solution needs a bit of thought as one size does not fit all build methods. Just be aware that timber shrinks quite a lot perpendicular to the grain so the more horizontal timbers you introduce the more vertical shrinkage you'll get. this may or may or be an issue.

 

If your walls are just not straight on plan then? each case needs assessed.

 

If you have a variation of 5mm over 5.0m then it looks like the brickie / person preparing the support for the sole plate has done a pretty good job!

 

 

 

 

Edited June 21, 2021 by Gus Potter

[jack1962]

Hi Gus

Thanks for the in depth reply.

I am fixing sole plate on concrete slab, cam i level it out perhaps using metal plate say every 1200mm under studs then fill with mortar? I have no overhang and i am 140mm soleplate with an average under hang of approx 10mm. 

On Checking the rest of the perimeter of the slab and taking from  the highest point there does not appear to be a variation of more than 10mm below the high point,,is slate an acceptable packer?  

[jack1962]

SABERREFIX HAND NAIL PLATE GALVANISED DX275 150MM X 75MM X 1MM 

Could i use them in the scenario below. When i have the level required under stud position, flip the sole plate back over and put a couple of nails to bold them in place then flip it back over and secure to concrete slab with my Hilti Hammer fixings?

 

The finished surface of the substructure supporting the timber frame should be reasonably level. However, where packing is required to ensure the timber frame or sole plate is level, the following three alternative options are acceptable.

The options given are for packing up to 20mm. Packing exceeding 20mm should be agreed between the timber frame manufacturer's engineer and NHBC.

1 Permanent structural packing under sole plate

The sole plate is levelled on temporary spacers. Once the first lift construction - wall panel and first floor floor structure (or roof structure in a single storey building) - has been erected, permanent packing is placed under the sole plate.

 
This permanent packing can be:

• free flowing non-shrinkable grout for the full length and width of the sole plate, or
• individual packers placed under each load point (e.g. stud or pos

[Russell griffiths]

I would look at a thick mastic and a foam damp proof course 

i would squirt the mastic on in two thick lines then bed in the foam filler then two more lines of mastic, this will take out any undulations. 

Get the frame up and secure down with straps once it has gone off, a few packers here and there to keep it from sagging. 

[Gus Potter]

Hi Jack.

 

On 21/06/2021 at 22:08, jack1962 said:

Hi Gus

Thanks for the in depth reply.

I am fixing sole plate on concrete slab, cam i level it out perhaps using metal plate say every 1200mm under studs then fill with mortar? I have no overhang and i am 140mm soleplate with an average under hang of approx 10mm. 

On Checking the rest of the perimeter of the slab and taking from  the highest point there does not appear to be a variation of more than 10mm below the high point,,is slate an acceptable packer?  

 

If fixing to a slab then  "underhanging" removes issues of the reduced edge fixing distance, that being the distance from the fixing into the concrete to the edge of the concrete. If over hanging then this problem arises.

 

At 10mm variation between the high point and low point you are in the ball park regarding mortar bedding thickness. If you have 5.0mm mortar bed at the high point then you'll end up with 15mm thickness of bed at the low point.. all within acceptable limits. The following is based on the assumption that you have not cast the slab to high! If you have then that is for another day.

 

Enough of the theory! ..some practical stuff. Here is a method of bedding a wall plate to get a quality job.

 

The first thing is that timber is not straight when you lay it down on site.. it may have been when it left the merchants!  Lay your wall plate down on plan and it will often have a bow, look at it sideways on elevation and it will be bowed that way too. And just to add to the dilemma it will also often be twisted.

 

Usually you have a DPC between the timber and the slab. Staple the DPC to the bottom of the soleplate. Next get some wet timber, say 100 x 22 mm soft wood. Rip this down lengthways so you have little strips of different thicknesses, say 4 x 22 , 6 x 22 , 8 x 22 and so on. Cut these into 150mm lengths.. like kindeling for the fire. Put the sole plate on the slab, pilot drill it so the screw can slip freely and part fix it down to the slab with say 120 mm x 5mm screws and plugs. As you do this get the sole plate as straight as you can on plan. Often you only need screws at 900 to 1200 mm centres so it's not to onerous to do. Also, you can use the screws to take the twist out as you can either put them close to the edge of the slab or more inboard. Fine to do as they are just temporary fixings and non structural.

 

Now work your way along it putting in the timber packers to get the top level. Try as best you can to keep the packers away from the stud positions. You'll not always get this bang on so don't worry. Just don't put them where you have a cluster of studs say taking high loads from lintels etc above or too close to the corners.

 

You need to slacken and retighten the screws as you go to get the packers in. You'll not get it perfect but do the best you can.  Once you have got it all as straight as you can unscrew the sole plate, put down the mortar bed and reposition the screws. Slowly tighten the screws while giving the top of the timber a tap down with a hammer. Leave it all to set. After a few days of dry weather the packers will shrink and you can wiggle them out easily. Point up the small holes they leave. Don't use dry timber for the packers as it will swell and lift the sole plate.. and you won't get them out later.

 

Leave the screws in place as this helps keep the sole plate in place while you are putting up the kit. Once the kit is up follow the SE's instructions for permanant holding down fixings and so on.

 

For all. The above is a bit lengthy but if you are self building and ordering a kit (TF) the manufacturer will often have a clause in their spec about how level the sole plate has to be. Deviate from this and it can let them shift the blame to you if something is not quite right with the kit. If you are going traditional masonry construction then you may have a trussed rafter roof. Again, the wall plate tolerances are covered in the manufacture's clauses.

 

Traditionally, less so now we used to make the bedding of the wall plate part of the brickies work package, particularly in Scotland when doing TF. This gives a clear line of demarcation. Brickies are not so keen on this now as..

 

All the best Jack and hope this helps, or you can adapt the above principles to suit your slab.

 

 

 

 

 

 

 

 

Edited June 22, 2021 by Gus Potter