Staircase making the risks

[JonR]

I know there are some of us here who make the odd staircase but i am wondering where we stand in regards to liability insurance for what we make and fit for people, my main reason for asking is that i have been asked to cost an unusual staircase which probably should go out to a specialist maker, but if i want to give it ago i need to cover my ar*e 100% i think. A basic description of it as best i can...

in Oak, 2 curved flights of 8 treads of a 1/4 circle turn from the left and right side of the gallery landing up to another landing which is some how hung from the vaulted roof above then a straight 4 tread flight up to the 2nd floor, now this is all hanging in the air from 1st to 2nd and open below to the ground floor in i guess you would call the Atrium.

If this was sitting on newel posts on the floor i may not be so reserved about giving it ago, it will need an engineer to calc the loadings on the roof and method of suspension of which i have some ideas on how to do this.

What do you think sort the appropriate liability insurance and get pricing or swerve it ?

[mark270981]

Hmmm I am wondering whether you would need Professional Indemnity insurance?

[Meccarroll]

This sounds interesting.

So is this two (curved) flights, left and right accessing the "first floor landing" (which is suspended from them) then on to the "second floor landing" using a straight flight from the "first lower landing".

If the above is correct maybe the lower part could be strengthened with steel support, it could pass through to the lower strings and onto the landing to bind the lower construction together. The lower construction could be bolted to concrete pads in the floor, which may be sufficient to support the top flight.

Take a look at this link, it may be useful to your design http://wooddesigner.org/

Ness Tillson has constructed many curved stairs and has many videos on utube showing how to construct them. If you contact him, he may be able to help.

It sounds like this project would be at least £20-30K range and up, so may be worth the input needed. A single curved flight is worth around £12K upward.

All the best with this if you decide to go ahead.

Mark

[JonR]

Cheers for replies chaps, i've just received an updated drawing from the builder its now a single semi circular flight of 13 treads so a lot less problems fitting and making...maybe


Sussed out how to post images finally

This is the original



its now this



I may suggest having glass balustrade and open treads with stub risers, feeling a bit more confident now with the simpler design but there still the liability side of things so i best give Swintons who does my basic liability insurance a call i thinks.

Re Ness Tilson i have watched some of his videos in the past a very clever chap.

Will update.

[Meccarroll]

What is the design for the ground floor flight? Looking at the drawings it has seven treads. Is it curved or straight?

Mark

[JonR]

Its straight Mark thankfully but who knows it could change, we did one like that a couple of years ago ill get some pics of that on. I have been reading up on glues to use for laminating the strings and handrail

and found this thread on Woodweb which has been enlightening

http://www.woodweb.com/knowledge_base/C ... _Tips.html

and Ness Tillson appears to just use normal PVA ?

any recommendations are welcome

[Meccarroll]

Its straight Mark thankfully but who knows it could change, we did one like that a couple of years ago ill get some pics of that on. I have been reading up on glues to use for laminating the strings and handrail

and found this thread on Woodweb which has been enlightening

http://www.woodweb.com/knowledge_base/C ... _Tips.html

and Ness Tillson appears to just use normal PVA ?

any recommendations are welcome

I have watched videos in which Ness Tillson seems to use PVA also but it's use may be limited to certain parts of projects, who knows. Most people seem to steer away from PVA when a project becomes structural in form, why I am not exactly sure (creep!!! ) but below is an extract on a thread started some time ago on the subject regarding "Glue for curved stair strings". I had a nice bit of input from the lads on here about suitable glues but the actual project never got started as the customer changed their mind about the stairs (too much money involved).

Re: Glue for Curved Stair Strings
by Meccarroll » Sun Dec 01, 2013 12:41 pm

Some good points have been made here.

Slainte, I did follow up on your comments and hear is the reply I received from Gruit (UKT)

With reference to your e-mail below regarding the selection of an adhesive for bonding wooden stairs...............

............So you really have two options a liquid epoxy to which you add filler powder to change the consistency to an adhesive or a manufactured adhesive systems.

The SP 106 is a liquid epoxy and so when used with the Micro Fibres and a small quantity of Colloidal Silica makes an adhesive with sufficiently high adhesion that all of the timbers mentioned in your e-mail will fail before the glue joint - as long as you prepare the surface correctly and the joint design is appropriate for the load pattern. Micro Fibres bulk the epoxy so that it fills gaps and the Colloidal Silica stops it from slumping and flowing before it cures.

The SP 370 is a pre thickened systems which just requires you to mix the resin and hardener together at 1:1 by weight or volume

The SP 370 is stronger and tougher (more impact resistant) than the SP 106, but the SP 106 is stronger than the timbers and so the strength advantage is of little interest. But the handling and ability to mix very small quantities easily is a great advantage. In fact it is one of the resin systems I keep at home for repairs and builds as you can mix a finger nail size resin to the same size of hardener for very small repairs or when you do not have quite enough.

They suggested I contacted: Marineware Ltd for the supply of the bonding materials as they only deal with orders of £5000 or more.

I was quoted approximately £40 ish (rough Guide as I can't quite remember, but I do have the figure on record) for 3kg (5lt equivalent) of the SP 106 system.

Many thank's for the help.

Mark

Try this email address for Martin at Gruit: [email protected]

Martin Armstrong
Composite Technologist
Gurit (UK)
St.Cross Business Park
Newport
Isle of Wight
PO30 5WU
England

tele +44 (0)1983 828103 (direct)
e-mail [email protected]
website http://www.gurit.com

And maybe a supplier:


Marineware Ltd
Unit 6 Crosshouse Centre
Crosshouse Road
Southampton
SO14 5GZ

tele 02380 330208
e-mail [email protected]

Mark

[JonR]

Thanks will be checking that out.

[Meccarroll]

Thanks will be checking that out.

Hi just wondered if anything came of this project? Only a few woodworkers tackle this type of work and I have not seen anyone on here do a set like this. I have seen kitchens galore, built in cabinets, doors, windows etc but no one has made a set of geometrical curved stairs on this forum to my knowledge as yet.

For some reason this style of stair fascinates me, hence the intreat and I'd love to see a project like this in progress on this forum.

Mark

[JonR]

I caught up with the builder last week actually who tendered for the job and he/they (2 brothers) said that the contract has still not been awarded yet but they are in the running with another builder. I did get a quote to supply the stairs which was £17k inc vat in Oak/cut string, the builder had a quote for something similar for a previous job and that was £28k, the maker expressed concern over supporting the stairs and rightly so, they stated that they would normally put a mid support in with that kind of staircase but i told them not worry about that just quote for the stairs only, i think the 180 degree turn is the problem and the weight on the outside of the stairs wanting to pull it away.

I would give it ago but only after discussing it with an engineer and getting design calcs for supporting it and connections details for the top and bottom, i do have access to a unit where i can make the formers and do the laminating which is handy if it should come off.


I will update if anything happens of course.

[Meccarroll]

Many thank's for the update and I hope you get this contract as it would be nice to see how you build and fit the stairs. One two or three mild or stainless steel rods suspended from the roof down to the string on the outside would probably take the outer load but would obviously be visible. Looks like an RSJ is shown in the drawings for the top support, cantilevers on the bottom would fit in but a structural engineer is a very good idea.

Mark

PS Merry Christmas

[Meccarroll]

Looks like 180 degree stair, the metal handrail probably helps with support.

https://youtu.be/ZY6Lw9ahoqw

[JonR]

Cheers, i have watched that with interest many times. Those strings are pretty hefty aren't they maybe that's the secret in keeping it free of a mid support, in my case add to that a bomb proof connection at the top and bottom all should be well.

Found this maybe you have seen it already

http://www.thisiscarpentry.com/2011/11/ ... -handrail/

[chippy1970]

I worked on a curved 2 flight staircase a few years back . For some strange reason though the architect decided to get someone to build it all in steel then we clad it in oak. The treads and risers went fine but the curved string wasnt level it was buckled and we tried gluing a veneer to it which wouldnt work. We ended up having it plastered. Not the greatest job ive got involved with lol.



https://www.facebook.com/csbiggscarpent ... 2922149281

[Meccarroll]

Cheers, i have watched that with interest many times. Those strings are pretty hefty aren't they maybe that's the secret in keeping it free of a mid support, in my case add to that a bomb proof connection at the top and bottom all should be well.

Found this maybe you have seen it already

http://www.thisiscarpentry.com/2011/11/ ... -handrail/

I have seen a couple of curved stairs were the string had been deepened at the top, presumably to allow for some support (maybe stub steel shoes etc) to extend under the stair two or three treads (allowing the strings additional support to sit on and fix to)......looked ok.

Mark

[rhrwilliams]

Bloody hell, thats a serious staircase ! Hope the plaster doesn't fall off. lol