BRANZ external stair handrails -45mm reqd vs 42mm balusters

Forums › Home Workshop DIY › BRANZ external stair handrails -45mm reqd vs 42mm balusters

fnarg7

10 posts

Wannabe Geek

#280656 31-Dec-2020 23:08

I'm trying to add some handrails to my external stairs (must've been without railings since 1972 when the unit was built).

Trying to do it to a reasonable standard and iaw the regulations, ie BRANZ D1/AS1.

"Balustrades of either 45 × 45 mm or 125 × 25 mm infill timber are fixed vertically"

1. The first question I have; why does industry (eg Mitre10 and Bunnings) readily supply 42mm x 42mm balusters/timber, but BRANZ states 45mm x 45mm? Surely it would make more sense for industry to supply timber that is in need to meet the building standard. I'm not able to paste links here, but to see what I mean go to Mitre10 or Bunnings and search '42mm' and you'll find lots of timber designated 'balustrade' or 'handrail' but none such in '45mm'.

I can't find any 45mm2 H3.2 timber, and really don't want to push it out to 50mm2, wanting to keep those balusters thin.

Does this ever become and issue on the building site where the building inspector gets out their tapemeasure and says 'na sorry that 42mm2 is not up to correct regulation...'

Likely I'll just carry on with 42mm2 - I won't be seeking code compliance, but doesn't make sense why there is that misalignment of requirements and supply.

2. second question - does the rail need to extend all the way to the end of the bottom step? Stair flight is 1.7m high and 2.0m long. I'd like to leave the last few steps without a rail so that it is easier to maneuver onto them from the side and enter the stair flight earlier. No indication in BRANZ F4 that I can see.

dazhann

465 posts

Ultimate Geek

#2628816 1-Jan-2021 08:13

We sell 45x45mm machine gauged at work, but it is actually 42x42mm. It would have been 45mm before it got gauged, but it’s still called 45. A lot of mg wood is called what it started as, causes a lot of confusion with the general public.

Bung

6480 posts

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#2628827 1-Jan-2021 08:58

MBIE are responsible for the D1 Access Routes document not BRANZ although BRANZ may have some relevant material.

"Handrails shall
have the same slope as the pitch line, begin
no further than the second riser from the
lower end of the stairway, and extend the full
length of the stairway they serve. Except that,
where the handrail serves an accessible
stairway or accessible ramp, a 300 mm
(minimum) horizontal extension shall be
provided at each end of the handrail, as
shown in Figures 9 and 25."

This reminds me that we have a handrail that stops short at both ends and I should fix it.

SomeoneSomewhere

1804 posts

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#2628892 1-Jan-2021 13:58

This should be 45x45: https://www.mitre10.co.nz/shop/non-branded-radiata-sg8-h3-2-wet-timber-50-x-50mm/p/615131

Odd that they're calling it 50x50; most timber now has the exact dimensions on it rather than initial.

It's essentially half of a 45x90/4x2.

larknz

1692 posts

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#2628919 1-Jan-2021 15:27

Most timber is sold based on its rough sawn dimensions, ie 100x50 and 50x50.

SomeoneSomewhere

1804 posts

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#2628921 1-Jan-2021 15:34

Yeah, it just seems weird that it's sold as that but the actual dimensions are what's printed on the timber itself and I think the timber packs.

neb

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#2628963 1-Jan-2021 17:34

dazhann:
We sell 45x45mm machine gauged at work, but it is actually 42x42mm. It would have been 45mm before it got gauged, but it’s still called 45. A lot of mg wood is called what it started as, causes a lot of confusion with the general public.

And more generally, X by Y usually isn't actually X by Y when you measure it, e.g. a good old 2 x 4 is actually 1 1/2 x 3 1/2, etc.

nickb800

2716 posts

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#2628965 1-Jan-2021 17:35

Even more complicated - it depends on the merchant. Consumer focused merchants like Bunnings and Mitre10 osteen just call it by the dressed dimension (ie 90x45). Placemakers etc will call it 100x50

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fnarg7

10 posts

Wannabe Geek

#2628981 1-Jan-2021 18:13

thanks everyone. I'm becoming less and less inclined to make it to the prescribed standards. It will still be functional and safe and within the intent of the rules, but given that the flight has small-rectangular sectioned galv metal stringers down both sides and some quirky metal brackets supporting the treads, it isn't easy to apply all the rules around securing the upright posts onto the stringers anyway. I'll extend the posts and install into the ground.

When would it likely become necessary to have it meet a code of compliance (or whatever it's called)? I mean the house has been bought and sold for decades without a problem. What would be the trigger for the council to take an interest? An accident? A tenant complaint? (possible future rental). Other work on the property requiring a building consent?

richms

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#2628998 1-Jan-2021 18:16

Other work usually. have seen people have to do crappy jobs raising deck rails and adding additional verticals on them when doing other work around the house needing the council to stick their nose into things.

Richard rich.ms