Building a half landing

[dnb]

A silly staircase question given that most people seem to not want to supply half landings. What are the requirements to consider for a half landing (I'm thinking mostly of loading)? Part K only really talks about sizing and positioning which are quite easy to meet.

[markc]

3 hours ago, dnb said:

A silly staircase question given that most people seem to not want to supply half landings. What are the requirements to consider for a half landing (I'm thinking mostly of loading)? Part K only really talks about sizing and positioning which are quite easy to meet.

Dont think I’ve ever seen anything for domestic loading of landings, but if you work on 5KN (0.5 tonnes) /m2 then you are safe.

[joe90]

Well I built mine as the stair co wanted way to much £. Simply 6x2 timbers using hangers onto walls at 400mm centres, stair co supplied both short stair runs and enough oak to board it and match the flights.

 

[ProDave]

Very similar to @joe90 stairs

 

 

Shown here as work in progress.

 

The 2 flights of stairs were 2 separate stairs from stairbox and the half landing was framed in place. Two 8 by 2's spanning the width and 4 by 2's spanning front to back. P5 chipboard floor.

 

Where it gets tricky is if you want e.g. an oak staircase without stair carpet, then you probably do need to get the whole lot made by the stair supplier.

[joe90]

2 minutes ago, ProDave said:

Where it gets tricky is if you want e.g. an oak staircase without stair carpet, then you probably do need to get the whole lot made by the stair supplier.

But mine was all oak, strip carpet up the middle which is why it’s framed in softwood but oak planks instead of chipboard.

[ProDave]

5 minutes ago, joe90 said:

But mine was all oak, strip carpet up the middle which is why it’s framed in softwood but oak planks instead of chipboard.

Well done.  I bet the challenge was getting oak planks for the half landing that matched the stair, or did stairbox supply those?

[joe90]

10 minutes ago, ProDave said:

or did stairbox supply those?

Yes, 👍

[dnb]

3 hours ago, ProDave said:

The 2 flights of stairs were 2 separate stairs from stairbox and the half landing was framed in place.

This is exactly what I am looking at. And from Stairbox too (at the moment - the only thing to change it would be my local stair builder chap suddenly becoming a bit less expensive and infinitely less busy)

 

I'm essentially aiming for the mirror of what @ProDave  and @joe90has done. I assume that the photo makes them look steeper than they actually are. If you don't mind me asking what rise and going did you end up with? I've got a bit of wiggle room with mine so I can use the space to make the stairs wider or making the goings longer. Both measurements are comfortably better than minimum standard already.

 

3 hours ago, joe90 said:

But mine was all oak, strip carpet up the middle which is why it’s framed in softwood but oak planks instead of chipboard.

Sounds difficult. Guess what SWMBO wants... At least she's gone off the carpetted open riser staircase.

 

Thanks all

[ProDave]

I can't recall the rise and going of mine, but the rise is close to the maximum allowed under building regs.  I had to fit the rise into 13 steps as it deliberately had to be offset, if both flights were the same, the bottom step would have been in front of a doorway so the bottom flight had to be shorter at only 6 stairs.

 

When it came to final measuring before ordering I had a bit more wriggle room on going, so made the going as long as i could which made the angle of the stairs about 41 degrees, comfortably lower than the maximum 43 degrees.

[joe90]

42 minutes ago, dnb said:

what rise and going did you end up with? I

Can’t remember but standard 42’

[Gus Potter]

16 hours ago, dnb said:

What are the requirements to consider for a half landing

 

10 hours ago, ProDave said:

Shown here as work in progress.

 

12 hours ago, markc said:

domestic loading of landings

Hello dnb.

 

The half landing needs to be compliant with the regs in terms of width.

 

@ProDave His photo is a good example to explore as to what you need to do SE wise and how you start checking / designing it.

 

First in terms of a domestic stair. The landing is just like a floor so the live loadings on the floor (people etc) are 1.5 kN/m² which is about 150 kg per m² 

 

If you have 18mm thick V313 say chipboard this will need supported at 400mm centres, if 22mm thick then 600mm centres under normal loading conditions.. no other hidden loads.

 

The next thing to do is to design the joists that support the chip board (landing) . As a rule of thumb if you take the span of the landing joist in feet, divide it by two and add two inches.. convert this to metric if you have to and that will probably work in terms of joist depth based on a 45mm (C16 grade) thick timber, subject to final checking. Final checking includes working out the self weight of the landing, any ceiling under etc and if the load goes onto the trimmer or side walls and what that load is.

 

Pro Dave's joists could span from the wall with window opening back to the trimmer at the top of the lower flight or side wall to side wall.  Can't see from the photo but the same principle applies.

 

Next thing to do is to work out the loading on the lower and upper flight of stairs. There are a number of different loads that the codes require you to look at. Evenly distributed loads and point loads. In general it's the distributed loads that govern the design. The loading on the stair flights that tend to govern are the self weight of the stair plus the live load (150kg/m²). The stair flight is like a roof rafter and often we assume that the stringers are simply supported at the bottom and top. Yes the outside stringers could be fixed to the side walls but let's assume they are not as the side walls may be non load bearing walls.

 

Now we can work out what loads the stringers are putting on the trimmer, add to that any load from the landing and this lets us design the trimmer. Say the landing joists span onto the trimmer. The trimmer is checked for the four point loads from the stringers plus the uniform load from the landing. In this case as we have point loads from the stringers close to the side walls we need to check carefully for both bending effects and shear effects at the ends of the trimmer. What we do though is to make the trimmer pretty stiff so that it does not deflect very much at all. Every bit of deflection adds to a "bouncy stair"

 

The next stage is to check all the joist hangers etc and any directly nailed connections.

 

There are a lot of ways you can put a stair like this together but hopefully this gives an insight into how you go about designing it structurally.

 

Now if anyone is intersted in how you design cantilevered type / winding stairs with no trimmers or central supports please post. These are fascinating to design and make work. Master stone masons have been doing this for centuries and the laws of physics have not changed. A lot of modern cantilevered stairs are designed with each tread as a cantilever extending out from the side walls but under the right circumstances there is another very elegant way of doing it that can deliver a great aestetic result. When folk look at them they may be inclined to think.. how does it stay up?..

 

 

 

 

 

 

 

 

[ProDave]

13 minutes ago, Gus Potter said:

Pro Dave's joists could span from the wall with window opening back to the trimmer at the top of the lower flight or side wall to side wall.  Can't see from the photo but the same principle applies.

Mine is a bit hybrid.  I have an 8 by 2 spanning side to side one at the front and one attached to the back wall.  I then span between those (between the top of the stair and the wall with the window) with 4 by 2's.  I did this to give maximum headroom inside the cupboard.

[Gus Potter]

58 minutes ago, ProDave said:

Mine is a bit hybrid.  I have an 8 by 2 spanning side to side one at the front and one attached to the back wall.  I then span between those (between the top of the stair and the wall with the window) with 4 by 2's.  I did this to give maximum headroom inside the cupboard.

Yes there are so many ways of doing it.

 

Say that landing you have is max 1200 mm wide .. ~4 feet.  4 feet /2 = 2 + 2 = 4 inches target joist depth at 45 to 50 mm wide in grade C16 or above timber.

 

Your 8 x 2. Say that spans tops 2.4m ( 8 feet) .. 8 /2 = 4 + plus 2 inches and extra inch for the point loads from the stringers = 7 inches ~ 170mm metric deep joist. That will probably work in terms of strength but you are looking to reduce deflection = bouncy stair.. so your 8 x2 is a good call.

 

Looks good to go Dave.

 

For all.. there is no point in having a good beam if the end connections (joist hangers / nails etd) are rubbish.

[ProDave]

11 minutes ago, Gus Potter said:

Yes there are so many ways of doing it.

 

Say that landing you have is max 1200 mm wide .. ~4 feet.  4 feet /2 = 2 + 2 = 4 inches target joist depth at 45 to 50 mm wide in grade C16 or above timber.

 

Your 8 x 2. Say that spans tops 2.4m ( 8 feet) .. 8 /2 = 4 + plus 2 inches and extra inch for the point loads from the stringers = 7 inches ~ 170mm metric deep joist. That will probably work in terms of strength but you are looking to reduce deflection = bouncy stair.. so your 8 x2 is a good call.

 

Looks good to go Dave.

 

For all.. there is no point in having a good beam if the end connections (joist hangers / nails etd) are rubbish.

The two 8 by 2's were chosen because.......  I had two lengths left over that were long enough.

 

The front one is supported mid point by the newel posts that go down to the floor so that will reduce deflection, and the back one, well that could have been anything, it is fixed to every single timber frame upright at 600mm centres.

[Gus Potter]

2 hours ago, ProDave said:

The front one is supported mid point by the newel posts

Dave .. was not sure if you had continued the newel post all the way down. But for BH folk and for simplicity had assumed that your good photo showed a clear spanning trimmer.

 

On the upside Dave.. given your neck of the woods I expect, as does a lot of my family that live on the islands, you will be putting on a bit of weight  on "for the winter months to keep you warm ", partying over the coming festive period.. I referenced a floor loading of 150 kg per sq metre.. there are some big fishing folk up your neck of the woods? 150 kg... would that would be their weight with no clothes on?

 

Of course we in the central belt of Scotland will be living on lentils in the lead up and during xmas.. have electric blankets (PV supplied of course) and be having a "quite time" at so don't need to worry about over loading stairs and floors. We will be miserable but convince ourselves we are happy.

 

You stair looks good by the way.

 

 

 

 

 

[dnb]

3 hours ago, Gus Potter said:

Now if anyone is intersted in how you design cantilevered type / winding stairs with no trimmers or central supports please post.

 

Thanks for a lot of good information. I think I have a good plan now. Now you mention cantilevers, an idea for the other staircase (that might not be possible with the space I have, but it would look good if it did work) comes to mind. Will try to do a sketch. It's much less urgent than the main stairs though.

 

5 hours ago, Gus Potter said:

no other hidden loads.

No piles of books this time. I promise

[markc]

Re the 150kgs/m recent evacuation from a house, woman weighing 180kgs, 2 big and 1 small paramedics, let’s say 260kgs for the 3 of them plus the 180 plus a stretcher/carrier (20kgs I think) that’s 460kgs plus self weight of stair flights all supported by a small landing.

oh plus two other family or neighbours who were also standing on the stairs watching … loads on landings soon add up!

[saveasteading]

7 hours ago, markc said:

460kgs plus self weight of stair flights all supported by a small landing.

Hence factors of safety. Some for load, material, and build quality.

And a lot of that weight is at the edges.

Then, most structures are governed by deflection limits...ie they flex and feel uncomfortable long before they break. I assume that the stairs did not fail in this instance.

[markc]

 I assume that the stairs did not fail in this instance.

no they didn’t