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November 24, 2011

House primary spiral stair what diameter do I need to comply.

You will find the answer in BS 5395 part 2 but it will not tell you the actual diameter required for a spiral staircase. The standard specifies the clear width required for different applications. For instance spiral staircases serving as the main house staircase would come under category B which requires a clear width of 800mm.

The definition of the clear width is the distance between the outside of the spiral stair centre pole and the inside of the handrail, this in practical terms is the width that you have available to walk up or down the stair. This is a good way of specifying the required size because if you have to escape down it in the event of a fire this width could be critical. Specifying the outside diameter of a spiral staircase does not really define the clear width because different designs and different styles have different sized centre poles and handrails which will in turn have change the amount of clear width.

None of the above really helps the questioner, what he really wants to know is how much area he needs to leave to accommodate a compliant primary spiral staircase in his new house design. The answer is about 2000 mm diameter, I say about because as you now know, without knowing the constructional details of a the specific spiral stair I cannot say for certain. Personally for design purposes I would leave if possible an area 2100mm square this would just about cover most models of spiral staircase that you are likely to buy. In my experience I have not found any modern designs of Category B compliant spiral stairs that are smaller than around 1900mm.

The only real safe way of answering this question is for you to choose your spiral stair model and ask the manufacturer what diameter will comply under BS 5395 part 2 as a main staircase in a dwelling.

The spiral staircase Doctor.

November 15, 2011

Do kit spiral staircases comply with BS 5395 part 2.

It is difficult to generalise on all manufacturers of kit spiral staircases, although what can be said is that they are all continental and almost all do their own load testing etc. aimed at their own national standards but not specifically for the British Standard. The chances are that there will be something within the British Standard that will not be covered in the Continental equivalent and visa versa. That is not to say that either is wrong just different. Theoretically all us EU communities are attempting to eventually bat on the same wicket, but in the current state of the union that looks less like a priority.

So the questioner has his eye on a nice kit staircase and he knows that if someone claims that it complies with the British Standard then it will be acceptable under the Building Regulations. That is perfectly true but a very difficult claim to make with any adjustable spiral stair kit. The ability to adjust means that the end user can in all probability adjust say the tread rise outside of the British Standard maximum therefore it would not meet the standard. So, why not make the adjustments so that they can only remain within the standards. Yes a good solution, but whose standards, the Italians or the Brits! When you make a kit product to sell on the world markets it has to have built in compromises in an attempt to keep everybody happy as much as possible. If you were to go to a reputable bespoke spiral staircase manufacturer you should be able have a staircase made that will meet all the nuances of the British Standard but you will of course pay for the privilege. Reputable kit spiral stair companies should also be able to advise you on which spiral staircases you can use and how you can use them for specific project to meet the main conditions of the British Standard. It would however be a reckless company who boldly stated that it totally complies with everything in the British Standard, unless the manufacturer has had it independently tested and approved by a qualified body. The heavy costs of this procedure means that no continental manufacturer is ever likely to go through this process just for their British market. The only kit spiral stairs that I know of that have been specifically tested to BS 5395 part 2 are the Klan and Civik ranges. The report runs to 50 pages and even then they can only approve the specific sample submitted which means one specific diameter and one specific floor-to-floor height. The document does however lend credence to a Local Authority approving these particular spiral stair models providing that you check that your specific height and diameter can meet the requirements.

None of the above proves that any other make or model of spiral staircase is not suitable under the conditions of the British Standard, it is just difficult to prove it. As I understand it equivalent European standards should be acceptable in the UK but getting a document from the continental manufacturer that is in a language that is understandable and acceptable to your Building Control department may prove to be another matter.

As always I recommend that you talk to someone 'who knows' who can advise you on your specific project before you go too far. Judging by the number of kit spiral staircases that get approved each year by various Authorities all over the UK you may have less trouble than you think.

The spiral staircase Doctor.

November 11, 2011

How do the Genius spiral stairs wooden handrail pieces make a helix if the tread rise is variable.

A highly technical question from a deep thinking gentleman.

This gentleman has spotted what the mathematicians amongst can see is a flaw in the geometry of making a helical wooden handrail for variable height kit spiral staircases out of short wooden sections. This is exactly what happens on spiral stairs kits such as the up market Genius range. However the manufacturer is on the case and has an answer for this problem.

Let me first explain the problem. A spiral staircase handrail forms a helix just like the spring on your pogo stick. To form this out of real wood is an expensive process requiring curves in two directions. It goes round in a circle on plan, the circle being the same diameter as the spiral stair. It also has to climb from the bottom to the top stair tread which is the second curve. OK all of this is possible but the helix will vary with every diameter and with every height. Therefore you have to make purpose designed helix for every stair. All kit spiral stairs like the Genius range require you to be able to change the height of spiral stair. Without this variability you would no longer have off the shelf kits, but would have to pay a lot more for a spiral staircase made specifically for your floor-to-floor height and diameter.

There is a further problem with kit spiral stair helical handrails, they are not only difficult and expensive to make, they are also big, awkward and very expensive to transport in one piece. So having made a helical spiral stair handrail the manufacturer cuts it into shorter lengths so that it can be packed in crate and transported. This process also requires the design of a method of rejoining the pieces together.

So the problem is how to make spiral staircase handrails that go round in a circle of a certain diameter but also curve in another direction to allow for various heights. The first curve is easy you just make a set handrails to suit the various diameters that you supply the stairs in, lets say four diameters. So each diameter spiral stair has its own handrail. The second curve is much more difficult. The only real solution is to also make a handrail not only for each diameter but for each millimetre of height of the stair height range. This is practically impossible as it would require the manufacture of thousands of variables. Failure to do this however means that the handrails will climb the spiral stair at a different angle of pitch to the stair treads, so it will get higher or lower in relation to the treads.

So the solution to this problem lies in the way that the handrail sections are joined. Instead of making the join between two handrail sections butt up hard against each other which would fix the angle of the second curve, the clever manufacturer supplies a clear tapered washer that fits between the two sections. By rotating the washer you can vary the angle of pitch a little on each join. This solves the problem, it is not a perfect solution but it works, and if you take your time with the washer adjustment you will achieve as near a perfect result as makes no difference. Unfortunately it does require you to align it by eye and tape measure as it would be nigh on impossible to produce any kind of tables that would help with this. Trust me it does work, I have seen Genius spiral stair handrails that have been assembled by people who were totally oblivious to the function of the tapered washer and just inserted them any which way. The result looked fine even to my highly critical eye. So worry ye not my mathematical friend the circle can be squared, or near enough anyway.

The Spiral Staircase Doctor

November 11, 2011

How do I get a loft room staircase in my Victorian terrace?

This is a Doctor Who Tardis problem, how to get a quart into a pint pot. There are many types of Victorian terraces but the one I am regularly asked about consists of front and back rooms with two bedrooms above and possibly a single storey scullery extension out the back.The staircase goes across the width of the building between the front and back rooms, access to the back sitting room being under the stair landing. In my opinion this design shows just how good the old folk were at getting the best out of a small space. Fortunately they were not hampered by the modern requirement for unnecessary things like bathrooms or kitchens with dishwashers and microwaves.

So a great design for your great grandparents but a nightmare for access to that nice big unused loft space. Unfortunately I have never found a simple answer in providing a loft staircase to this type of property. If there was a simple answer it would have long ago been fashionable and would almost certainly have been adopted by the original Victorian designer. I am always amazed at the number of young people who come to me with the revolutionary idea that they have discovered of buying in a two bedroom terrace and simply making it a three bedroom by using the loft space. Believe me if it were that simple the whole street would already have three bedrooms.

The basic problem is that a loft staircase will require floorspace on the first floor and the only floorspace usually available is found by reducing one of the already small bedrooms. What about putting one stair over the other I hear you cry. That is a good solution but unfortunately access to the loft stair will still require a corridor making in one of the bedrooms to access the foot of the loft stair, so there is nothing to be gained in floor area.

So there is no easy solution and somewhere along the line it is going to cost you space in the existing bedrooms. You may be able to reduce that space by using a space saver stair like the Karina but it will still take up some space and will of course require approval by the Local Authority. A fairly common but expensive solution is to rip the entire room layout apart and end up with a through lounge and a new stair running front to back. You may also be able to convert that stair to a two storey spiral staircase to get access to your new loft room as well. However been warned that You will probably find that the diameter of spiral staircase required by the Regulation people may make this option too large to be workable in the narrow width of your terrace.

I am sorry that I cannot come up with a magic answer, believe me if I could I would be a very rich and happy old man.

The Staircase Doctor

November 07, 2011

Why have I got a plastic handrail in my spiral stair kit.

Why have I got a plastic as well as a wooden handrail in my spiral stair kit.

This questioner actually wrote for advice because she had bought from a supplier a Mr Step Gamia Wood spiral staircase with a wooden handrail. When it arrived the crate contained a plastic tube handrail with a wooden handrail as a separate item. Her complaint was that she was paying for two handrails when she only ordered one. Her supplier was not sympathetic saying only that that is the way they are sold.

Although it seems a strange way to do business the supplier was actually right, the Gamia Wood spiral staircase kit is pre boxed with a moplen plastic handrail, the wooden handrail is then sold as an extra add on. In reality the Moplen plastic handrail which looks like a corrugated black plastic land drainage pipe probably costs the manufacturer virtually nothing, so leaving it in the box is a cheaper option than opening it up and repackaging the wooden handrail.

I do agree however that it is not the best way to present a product. Never mind the cost, it can also be very confusing when your installation instructions do not show how to put together the wooden handrail and your box contains a drainage pipe that you spend an hour wondering where to fix it on the spiral stair.

I have on many occasions in the past pointed out to Rintal the Italian manufacturer of the Gamia Wood spiral stair, that customers did not like this situation and were complaining. I never managed to get them to change anything which I think is shame. However to be fair to them the Gamia Wood spiral stair is an entry level kit that is sold at a remarkably cheap price, so maybe the ownership of a bit of spare drainage pipe is a price worth paying if cost is an issue.

The Spiral Stair Doctor