Timberlok vs Coach Screws. is there a difference?

[Thorfun]

1 hour ago, Mr Punter said:

I don't like cantilevered glass balustrade.  You can't lean on it comfortably or hold it.  I prefer a stainless handrail on top.

 

Funny, with timber handrail and balustrade, the BCO will never ask for calcs or BBA certs.  At most they may see if it wobbles or deflects excessively.

we wanted the clean aesthetics from the landing so as to not interfere with the view up and through.

[Thorfun]

13 minutes ago, saveasteading said:

Don't worry about that. Timber is good for this, and Glulam especially so.

More important is to drill a very neat hole so that the thread bites into the sides of it.  Then when you are screwing it in, you are cutting h threads into the timber and not trying to force it.

was 100% going to pilot hole.

 

14 minutes ago, saveasteading said:

The other weakness might be the screw head bursting through an aluminium frame that is being forced. Hence big heads and washers will spread the load.

this is interesting. I was planning on using washers simply because the hole for the fixing is quite wide and I thought washers would reduce the risk of the screw head going through. didn't know about using them to spread load!

 

15 minutes ago, saveasteading said:

The photos are  great help as well as interesting. Very tidy. Is the nearer glulam spiked into the adjacent floor to give it stability?

thanks. tbh, I don't remember how they fixed it sorry. and I don't see any specific photos of how it was done.

[Thorfun]

thanks all so far for the responses. another thing if I may. we have 14mm engineered wood flooring on that landing fitted with an underlay (so floating). my builder mate said he was concerned about fixing through the floating 'thin' layer and down into the chipboard and subsequent timbers and I should cut the finished floor out and fix directly to the chipboard and through. that seems to make sense to me but I'm struggling to understand the reasoning behind it as surely the fixing will then go down in to the timbers anyway so why does it matter if there's a thin floating floor between the profile and the solid timber?

 

any of you knowledgable folk care to shed some light on that one please?

 

 

Edited February 26 by Thorfun
added photo

[joe90]

24 minutes ago, Thorfun said:

fitted with an underlay

These are usually very thin, how thick is yours? Frankly m12 coach screws every 300mm will crush that IMO and the engineered boards will spread the load even further.

 

i take @saveasteading ,s point about heads pulling through the aluminium so steel washers would be good, as big as possible, penny washers and cut down width wise to fit in the space.

 

(what I don’t get from the pics above it shows the bolt heads below an aluminium web so does this have holes to enable bolts to be fitted to the bottom rail? )

Edited February 26 by joe90

[Thorfun]

1 hour ago, joe90 said:

These are usually very thin, how thick is yours? Frankly m12 coach screws every 300mm will crush that IMO and the engineered boards will spread the load even further.

14mm. 3mm veneer and 11mm ply (approx). I'm not sure from your answer if the crushing is a good thing! it doesn't sound it to me and it sounds like there might be a slope as the underlay and flooring is crushed?

 

1 hour ago, joe90 said:

(what I don’t get from the pics above it shows the bolt heads below an aluminium web so does this have holes to enable bolts to be fitted to the bottom rail? )

yes. do these photos help?

 

 

Edited February 26 by Thorfun
added a second photo

[joe90]

6 minutes ago, Thorfun said:

14mm. 3mm veneer and 11mm ply (approx). I'm not sure from your answer if the crushing is a good thing! it doesn't sound it to me and it sounds like there might be a slope as the underlay and flooring is crushed?

No the engineered flooring won’t crush but the thin underlay (foam?) will slightly and I bet it’s about 2 or 3 mm only 🤷‍♂️

6 minutes ago, Thorfun said:

does this photo help?

No 🤣 how do you get the screw through that upper web, does it have a hole to give access to the bottom ? Ah, you said “yes” to holes….

Edited February 26 by joe90

[Thorfun]

Just now, joe90 said:

No the engineered flooring won’t crush but the thin underlay (foam?) will slightly and I bet it’s about 2 or 3 mm only 🤷‍♂️

5mm

 

4 minutes ago, joe90 said:

No 🤣 how do you get the screw through that upper web, does it have a hole to give access to the bottom ?

yes. the screw just fits through.

 

[joe90]

Ah those photos came to me late.   IMO (others may disagree) 5mm foam under engineered flooring won’t cause a problem because the engineered flooring will spread the load far more than that ally profile would, 200mm screws into the glulam with steel washers will be suffice. Am I qualified as an SE, NO, but years of practical knowledge and a tendency to over engineer has stood me in good stead. I would be interested in other opinions.

[Thorfun]

ok. I sent the information to a friend who's a civil engineer and he sent me the following table which I believe is for the fixings the manufacturer used for their testing

 

 

the manufacturer states that their tests were performed with FISCHER FAZ 11 12/10 fixings and my engineer friend stated that if I can get timber fixings that have a 10kN pull out I'm all good. he then said

 

Quote

An m12 coach screw with 90mm thread going into the structural beams below works, I would of suggested a Hilti screw but the head will break off at 5kN so needs to be a TIMco din571 or equivalent, you will need to pre-drill, suggest just get the 150mm long ones

 

so I'll be looking for TIMco din571 or equivalent M12 x 150mm coach screws!

 

I asked him about the floating floor and he said

 

Quote

You could core a hole down to the structural timber to match the balustrade hole spacing and use a steel pipe as a sleeve and tighten it down, leaving the floor still floating so a small gap

 

which sounds like an interesting idea and also mitigates the concern my builder mate has about the floating floor. although I would have to buy some steel pipe!

 

I hate to tag you @Gus Potter but I'm going to anyway (sorry!). are you able to cast your eye over the above and see if you agree with the findings please? and any other recommendations before I put this to bed and get on with doing some work?

Edited February 26 by Thorfun
reworded bits to make a bit more sense, I hope!

[Mr Punter]

21 hours ago, Thorfun said:

we wanted the clean aesthetics from the landing so as to not interfere with the view up and through.

 

If you specify low iron glass you won't get the green tinge.

[Thorfun]

5 minutes ago, Mr Punter said:

 

If you specify low iron glass you won't get the green tinge.

Thanks, but way too late as it’s all sitting in the house ready to be installed. 

[Alan Ambrose]

I think Gus did a similar calc for someone a few month’s ago on BH. Is one possibility to put it together and check that it supports the load that I believe he specified then … with a safety factor…

[Thorfun]

7 minutes ago, Alan Ambrose said:

I think Gus did a similar calc for someone a few month’s ago on BH. Is one possibility to put it together and check that it supports the load that I believe he specified then … with a safety factor…

Not seen @Gus Potteron here for a while. Would be great to get his input. Don’t suppose you have a link to that previous thread do you?

[saveasteading]

I am nervous about fixing it over a flexible surface. It will rock if shaken, and crush the underlay. Then it moves even more etc.

I've had a steel barrier come loose (rawlbolts to concrete) through repeated pushing by children, because once it starts to rock it becomes a game/ challenge.

Perhaps if tightened down hard enough the floor will compress and resolve this. I would do this by fixing the whole system, then repeatedly tightening from end to end

That brings us back to the weakest link being at the nut to aluminium interface. It  needs hefty steel washers or plates.

 

I've seen steel cladding sheets ripped off screw fixings. The sheet fails before the screw. Aluminium is much softer.

I am rather shocked that the manufacturer doesn't specify how to fix your rail in any way.

 

On  a positive note, If the ends are also fixed into walls or at returns then this issue will be much reduced.

 

@Gus Potter sometimes looks at my input so I'll @ him too, but he is probably busy doing paid work.

Don't panic though.  steel coach screws n every fixing hole, with washers, tightened up til the floor compresses and the screws stop tight, and all is probably ok. Fixing direct to the floor board is best though.

 

[Thorfun]

52 minutes ago, saveasteading said:

I am rather shocked that the manufacturer doesn't specify how to fix your rail in any way.

they do. just in to concrete. it's "not tested in to timber" seems to be the stock answer and so they cannot advise.

 

53 minutes ago, saveasteading said:

On  a positive note, If the ends are also fixed into walls or at returns then this issue will be much reduced.

simply not possible now. well, it is but it'll involve way too much upheaval at such a late stage in the build I don't want to do it. plus the frameless balustrade has already been bought and we don't have the money to get it re-done. 😞 

 

54 minutes ago, saveasteading said:

Fixing direct to the floor board is best though.

yeah, that's what my builder mate says too. I told him about my engineer mate's suggestion of coring through to the timbers and using steel pipe as a spacer and he was a bit sceptical. said things along the line of "he's thinking like an engineer" which wasn't a slur but more that it's a different way of approaching the issue. I'm sure both ways will work and it would come down to whether I trust science or experience!

[joe90]

I agree that steel washers are a good idea above soft aluminium, however, the system must be tested to be fit for purpose. I still say engineered ply above the underlay will spread the load over a much greater surface so think it will be fine. Still if the engineered timber can be lifted a section of the foam where the bolts are could be replaced with 5mm aluminium/steel/ hardwood. 

[saveasteading]

3 hours ago, Thorfun said:

they do. just in to concrete

what do thy say should be used into concrete? the fixing into timber isn't my concern, rather the aluminium and the underlay.

 

3 hours ago, Thorfun said:

"he's thinking like an engineer"

Engineer/ ingenuity.  You've  asked for a way to do this without removing the floor covering...spacers is his answer. 

[markc]

As a balustrade the loads are relatively low UNTIL someone runs or falls into it, with the channel fixed flat into a hard surface the bottom corner of the channel becomes the point of rotation and the fixings are in tension.

if spacers are placed under the channel the point of rotation becomes the edge of the spacer and localised around the fixing, this changes the fixing load to more bending moment than tension and the calcs become much more complicated.

also if spacers are used, the channel is subjected to localised stress around the spacer and could tear out when an increased load is applied.

much better and safer to fix the channel hard down with full contact on a solid surface.

[Russell griffiths]

How about. 
drill all the way through, down through the ceiling, then countersink in your washer and nut. 
 

then you can do two things. 
either get the holes repaired, it’s only plasterboard and a bit of skim. 
or put a wooden trim around that edge of the ceiling. 
either an mdf trim painted to match the ceiling, or maybe a nice piece of hardwood stained to match your doors or other trims in the house. 
 

just a thought. 

[Russell griffiths]

Or you could

drill a deep hole 150mm and resin fix in a threaded rod joiner, these are about 50mm long. 
when this has gone off you can insert a bolt from the top to go into the hole and pick up the stud joiner that is already epoxy fixed in place. 

Edited February 28 by Russell griffiths

[Thorfun]

23 minutes ago, markc said:

As a balustrade the loads are relatively low UNTIL someone runs or falls into it, with the channel fixed flat into a hard surface the bottom corner of the channel becomes the point of rotation and the fixings are in tension.

if spacers are placed under the channel the point of rotation becomes the edge of the spacer and localised around the fixing, this changes the fixing load to more bending moment than tension and the calcs become much more complicated.

also if spacers are used, the channel is subjected to localised stress around the spacer and could tear out when an increased load is applied.

much better and safer to fix the channel hard down with full contact on a solid surface.

the best reason I've read so far to fix to the solid surface. thank you.

[Thorfun]

6 minutes ago, Russell griffiths said:

How about. 
drill all the way through, down through the ceiling, then countersink in your washer and nut. 
 

then you can do two things. 
either get the holes repaired, it’s only plasterboard and a bit of skim. 
or put a wooden trim around that edge of the ceiling. 
either an mdf trim painted to match the ceiling, or maybe a nice piece of hardwood stained to match your doors or other trims in the house. 
 

just a thought. 

it's a possibility but if the coach screws will do the job then I'd rather do that. but this will be kept in the recesses of my brain as a potential option.

[Thorfun]

9 hours ago, saveasteading said:

what do thy say should be used into concrete? the fixing into timber isn't my concern, rather the aluminium and the underlay.

they tested using FISCHER FAZ 11 12/10 fixings in to concrete and from the spec sheet of those it was determined I need fixings with a 10kN pull out resistance. which led to the M12 x 160mm coach screw decision.

 

9 hours ago, saveasteading said:

Engineer/ ingenuity.  You've  asked for a way to do this without removing the floor covering...spacers is his answer. 

indeed. it was an ingenious solution but I just don't know if it was the right one. especially considering @markc's explanation of the forces involved when using the spacers.

[joe90]

8 hours ago, saveasteading said:

the fixing into timber isn't my concern,

+1

9 hours ago, saveasteading said:

rather the aluminium

Which must be tested and sold as fit fir purpose 

9 hours ago, saveasteading said:

the underlay.

 

9 hours ago, joe90 said:

a section of the foam where the bolts and Chanel are could be replaced with 5mm aluminium/steel/ hardwood. 

But I still recon the hardwood flooring will widen the footprint of rotation greatly to become negligible when fastened down.

[Thorfun]

6 minutes ago, Russell griffiths said:

Or you could

drill a deep hole 150mm and resin fix in a threaded rod joiner, these are about 50mm long. 
when this has gone off you can insert a bolt from the top to go into the hole and pick up the stud joiner that is already epoxy fixed in place. 

this is an interesting idea indeed. but anyone have a calculation as to the pull out resistance that this will have? I'm looking to replicate the manufacturers testing and ensuring that there is a 10kN pull-out resistance at the moment, at least that's the current thinking.