# Forum Home Renovation Stairs, Steps and Ramps  Cupping in F14 treads

## ringtail

Hi all, any of you old timers ( with respect) got any good tips for stopping the cupping of 250 x 50 F14 appearance grade treads ( external). I have a job on where the customer is insisting on steel stringers with the 250 x 50 tread. Normally its not a problem with a housed timber stringer that restrains the tread a lot, but they look crap when they have shrunk on steel stringers. I was thinking of maybe putting some ripped kwila on the end grain ? I remember reading somewhere about putting a cut in the underside of the tread ? 
Cheers

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## Gaza

maybe use F17 / F27 which has been kiln dired. 
run a grove in underside. 
or even use two 125mm with 3mm gap between them

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## ringtail

Thanks gaza. A few issues - Ive thought about the 2 treads but the way the mount is drilled would put the bolt at the rear of the back tread and the front of the front tread and there isnt enough meat in the mount to drill a second hole for each tread. The mount on the scotts steel stringers are not a plain angle, they have cut aways in them. Secondly  F 17 will shrink just as much as F14, KD F17 is a non durable product and F 27 is too expensive for the client. It just comes down to him not wanting to fork out for a real staircase.

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## Gaza

> Secondly F 17 will shrink just as much as F14, KD F17 is a non durable product and F 27 is too expensive for the client. It just comes down to him not wanting to fork out for a real staircase.

  you can get F17 spotted gum or blackbutt which is durable, there is next to no srinkage for F17 as it is kiln dried (the boral & parkside stuff is) 
F14 is green as with a high M/C

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## dukekamaya

I agree use kiln-dried hardwood. There are several durable species available in F17 kiln-dried

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## ringtail

It would probably end up been ironbark up here. Why do all the timber suppliers up here say that F 17 KD is not suitable for exterior use ? They reckon you have to go F27 KD to get the DC 1

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## dukekamaya

> It would probably end up been ironbark up here. Why do all the timber suppliers up here say that F 17 KD is not suitable for exterior use ? They reckon you have to go F27 KD to get the DC 1

   Thats crazy, there are many species such as yellow stringybark, silvertop ash or blackbutt which are available in KD F17 and are durability class 1 or 2.

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## ringtail

I know that just about all those species are not readily available in Qld. Ive got a mate in Port Macquarrie that gets blackbutt really easily, but up here its a special order. Just about all DC1 timber up here is either ironbark or turp. DC 2  is common as . Google *nerangba timbers* and have a look to see what I mean about the KD F17. These guys are not my supplier, but Ive been told by my guys aswell. I personally dont see the drama but I'd hate to get caught out

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## dukekamaya

Durability class 2 is fine for outside. 
Glad you can get turpy up there, its very difficult to get here. Even ironbark is becoming harder to source - pretty much anything over 150x150 now will almost always contain heart. 
What are you paying for KD F27 up there? 240x45 in blackbutt goes for about $40/metre

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## dukekamaya

Had a look at their website, I would like to know what species the F17 is.

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## Gaza

> Had a look at their website, I would like to know what species the F17 is.

  i am guessing vic ash,  
do you guys use nail plated hardwood in QLD much, i have not seen it in 10yrs in syd.

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## ringtail

My supplier is pretty dear compared to nerangba's prices ( but the same as just about any other yard in the area ). For example  240 x 45 DC 1 ironbark F27 KD is $ 45 .30 + gst last time I looked. But even F17 Ironbark is dear. 200 x 75 DC 1 F 17 is $ 40.53 + gst. The turp is getting harder to get, with most people having to wait a little while or just having to go with ironbark. Kwila is going pretty well up here though. Prices are pretty good for solid and finger join lam. Even bunnies are selling 90 x 90 lam posts for $ 20 / mt incl. Just out of interest, what is the F rating of kwila - Ive been told its near enough to F27 - true ? 
Gaza, the only nailplated stuff is over 5.4 in KD I think, but overall, most people are now going for LVL's or glu lam instead of HWD. Its cheaper, straight and true, turns up quick, takes H3 treatment well and  lenghts upto 13 mt. What more could you want.

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## dukekamaya

Until recently merbau/kwila had been coming into Australia non-graded which has long been a grey-area as far as councils/engineering goes.
It is mostly now F27 though the posts are not structually graded. 
Is the ironbark up there your talking about definately kiln-dried? We can't generally get structual KD ironbark in NSW - its all unseasoned.
If its kiln-dried and F17 it must be ordinary as KD ironbark goes F27,F34 and F43 in the good quality stuff 
Im not sure why they would have F17 Vic Ash up there, we don't even use it in NSW much. Nearly all our KD F17 is Yellow Stringy or Silvertop Ash

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## dukekamaya

Just reading your post again, the F17 200x75 is definately unseasoned - you can't kiln-dry timber harder than about janka 6 any thicker than 50mm

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## ringtail

Yup, that 200 x 75 is unseasoned F17 that I was going to use for a deck but ended up going the LVL's because I could afford any shrinkage.  They tell me they have KD but whether it turns out to be who knows.I see on nerangba timbers website the prices of their kwila are pretty cheap, but is there dodgy stuff and good stuff ? What are your thoughts on the FJ 90 x 90 kwila posts ? A lot of guys up here ( me included ) have been using the FJ Laminated 140 x 42  kwila for hand rails but have been told recently not to use it in sun exposed areas because it will open up ? ( this is after the timber suppliers have been raving about it as a durable handrail fully exposed ). Si if the 140 x 42 opens up in the sun, how are the posts going to stand up to it if they are clear finished ?

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## dukekamaya

We've been selling the 88x88 F/J merbau posts for at least 5 years and haven't had any issues. I'm told the adhesive used is to Aust/NZ standard for outdoor adhesives.
Merbau is a good timber with a durability 1 above ground rating, it doesn't fair so well in ground though with only a D3 in ground rating.
We only deal with the F/J laminated posts, all other end sections are solid. 
Another worthy note is the 'suspect' way merbau/kwila is clear-felled in Asia and Indonesia. I'm told it is or soon to be banned in North America

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## Gaza

i dislike merbau, i think we should use Aust timbers and not have our money used to destroy other countries forest's. 
and that DNA merbau what are the timber importers working at CSI now, what a load of rubbish.

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## ringtail

I like the FJ posts because you stand half a chance of getting something straight  - ish unlike most of the F 14 / 17 posts - cheaper too. Why dont they start doing the same thing with aussie                hardwoods ?    cost  ?

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## dukekamaya

> I like the FJ posts because you stand half a chance of getting something straight - ish unlike most of the F 14 / 17 posts - cheaper too. Why dont they start doing the same thing with aussie hardwoods ? cost ?

   Nail laminated F27 kiln-dried posts have been available for a long time in Aussie hardwood

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## ringtail

Really. Ive never seen them, then again Ive never asked for them either. They must look like crap though eh ? Couldnt really use them for appearance stuff though I guess ?

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## dukekamaya

Its more the price that puts people off - its far cheaper (about half the price) to laminate 2 pieces of 90x45 F27 together then dress to 85mmx85mm to remove the pencil rounds

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## ringtail

Learn something every day eh

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## dukekamaya

I try to everyday - keeps the brain active

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## ringtail

Today I learnt ( again ) why chippies dont like painting. Slow learner.

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## Bloss

> Today I learnt ( again ) why chippies dont like painting. Slow learner.

  That's why we have painters - they never learn . . .  :Biggrin:

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## ringtail

Can you believe I did more today. Oh well, at least its done properly. How does napisan go at removing paint from new, yet to be washed merbau ( just tiny little spots - I'm not that messy - did forget the drop sheets though)

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