Building Underhouse - Termite Prevention

[deltoid]

Our house has about 2 metres clearance underneath and I am going to build a little lock up under there to put my powertools and other valuables.

Now I plan to use H3 treated timber and I do not intend on having the timber directly touching the slab anywhere (it is an old slab full of cracks and joins).

My problem is the wall which will have a door way on it. As you can see in the attached picture. I plan to use a Steel U-Bracket (I think this is what they are called, basically you dynabolt them into the slab then you screw your timber into them) for the corner of the wall where the door way will be. However as you can see in the picture. At the top of the wall I have nothing securing it to the joists (and as such it will most likely wobble).

What should I do here? I was thinking considering I'm using the U-Bracket on the base if Termites were to get into the wall I would see their mud tunnels on the u-bracket so it'd be safe for me to just directly join the stud to the joist beam above it which would make it stable.

Any better ideas?
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[ringtail]

Is that a joist on the stumps ? it should be the bearer with the joist then sitting on top of the bearer. I have just finished doing exactly what you want to do - old crappy slab ( or I should say 50 slabs layed next to eachother, all cracked). I just used a 70 x 45 CCA bottom plate with damp proof underneath, dynabolted to the " slab ", T2 top plate to the under side of the bearer then framed as normal with T2. Sheeted with FC sheet. I didnt take the wall above the bearer, my theory been that any termite action will be seen as they go up the bearer and still have 125mm of joist to get up before getting to the floor. Good ventilation through the bearer to joist gap aswell, without compromising security.

[TermiMonster]

Deltoid,
I think you are correct. Just make sure you get the brackets that don't have hollow steel rods (get the one's with solid rods).
cheers
TM

[deltoid]

Is that a joist on the stumps ? it should be the bearer with the joist then sitting on top of the bearer. I have just finished doing exactly what you want to do - old crappy slab ( or I should say 50 slabs layed next to eachother, all cracked). I just used a 70 x 45 CCA bottom plate with damp proof underneath, dynabolted to the " slab ", T2 top plate to the under side of the bearer then framed as normal with T2. Sheeted with FC sheet. I didnt take the wall above the bearer, my theory been that any termite action will be seen as they go up the bearer and still have 125mm of joist to get up before getting to the floor. Good ventilation through the bearer to joist gap aswell, without compromising security.

Do you have any photos? My wife is always hassling me about how poorly my imagination is with these things. I have trouble picturing what that would look like in my head.

I thought of a way to make the wall stable whilst not joining the wood to the joists (sorry, it could be a bearer, I am not up with the lingo. It is the beams that run parallel to the floor).

If I run that beam across the top it should do the trick.
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I will be trying to get the solid rods, is there a way to tell by looking at them if they are hollow or not (I assume they weld a base onto them so I can't see the core of the rod). It should be a dry area anyway so rust shouldn't be a problem so, so long as the base is welded on it should stay there but I'd prefer solid for the piece of mind.

[deltoid]

Also, what sort of wood should I be using. This structure will be under the middle of my house, so it shouldn't get wet unless I hose under there.

When I had my last termite inspection a few weeks back I told him what I was planning and he said just to make sure the wood is soaked in the insecticide rather than it painted on (otherwise when I cut the wood I'll be exposing non-treated wood and allow the little buggers a way in).

I was thinking H3? Is that the correct one to use?

[ringtail]

A few piccies for you.

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80040

80041

I used CCA bottom plate and T2 for the rest of the frame - all of which are pressure treated for termites

[deltoid]

Looks good. So you basically have the bottom plate sitting on the slab?

I was thinking of leaving a gap underneath for ventilation as there are parts under the house which don't have great airflow and get quite stuffy, so was thinking by leaving a small gap at the bottom and top it'll help with that (and with the termites).


One problem I do have though which I'm unsure of at the moment, is one of my stumps is a steel pier. I'm not sure how I will secure the wall frame to it. I am using dynabolts for the concrete stumps, but not sure what to use to secure to the steel stump.

Any ideas?

[Bedford]

One problem I do have though which I'm unsure of at the moment, is one of my stumps is a steel pier. I'm not sure how I will secure the wall frame to it. I am using dynabolts for the concrete stumps, but not sure what to use to secure to the steel stump.

Any ideas?
You can bolt to the steel pier, but you shouldn't use dynabolts into concrete stumps as they expand and can crack the stump.

[deltoid]

You can bolt to the steel pier, but you shouldn't use dynabolts into concrete stumps as they expand and can crack the stump.

Thanks, I was just talking to my dad and he said the same thing. He said to just drill a hole through both sides of the steel stump and then put a bolt through.

Oh, I didn't think of that with the dynabolt, makes sense though. What should I use instead of dynabolts?

[jago]

Invest in a decent cobalt bit to drill through steel it will make your life a lot easier.:2tsup:

[Bedford]

I think you'd be better to wrap some flat steel around it with a bolt through it, so it clamps to the concrete stump.

[deltoid]

Hmm, is there some kind of steel strap thing I can buy or is this something I'd make?

[Bedford]

You could probably use hoop iron, or bend up some 50x3 mild steel flat bar to shape.

[deltoid]

You could probably use hoop iron, or bend up some 50x3 mild steel flat bar to shape.

Thanks for the diagram Bedford. That made it easier for me to understand. So basically the wall will be secured to the pier by the tension of the steel strap?

I've been looking into which timber type to use, I think H3 will be overkill as it will not be exposed to the elements.

I'm thinking T2. If you cut T2 do I need to reseal the end?

[Bedford]

. So basically the wall will be secured to the pier by the tension of the steel strap? Yes, put one top and bottom.




I'm thinking T2. If you cut T2 do I need to reseal the end?
Not sure on this one, sorry.

[jago]

I used Terminator T2 90x 45 mm framing and the fact sheet that the suppliers gave me said that T2 ends or cuts do not need treating...

They come with a 25 year termite warranty and are treated with Tanalith T and linseed oil the blue colour fades and is a marketing thing to show that they have been treated and are suitable for use south of the the tropic of Capricorn and Red for North.

[deltoid]

I used Terminator T2 90x 45 mm framing and the fact sheet that the suppliers gave me said that T2 ends or cuts do not need treating...

Ok so the T2 stuff I can get from Bunnings should do the trick?

[ringtail]

Sorry for the late reply, been getting ready to pour footings. Go the T2, as jago said no need to do the cuts.

Yes I dyna bolted the 70 x 45 CCA bottom plate to the slab with a damp proof membrane underneath.

You could use chemset into the stumps, but the metal strap idea is a good one too

Could bolt right through the steel post or just use long self drilling metal thread scews with a hex drive head ( like a roofing screw but has a thread for the seel and a little drill bit on the end) they work well provided you dont over tighten them and snap them off. 1 every 500 mm would do.

Needless to say, try and get the straight bits of timber from the rack. Have a good look at them before selecting. Mark all of the bows in the timber with an X, and make sure when you frame up the wall that all of the X's are the same way - otherwise the wall will look like a snake

[deltoid]

thanks for the advice ringtail. May I ask what Chemset is?

I was talking to my dad about securing to the stump tonight and he suggested drilling a 10mm hole in the stump, then hammer some dowel into the hole and then use a timber screw to secure the stud to the dowel.

It wouldn't cause the same expanding like the dynabolts but would this cause problems?

[deltoid]

Hey, this is what I've got for the design of the wall with the doors on it (the other walls should be just simple stud walls so I'm confident I have that under control).

I still haven't decided exactly how to secure the studs to the concrete piers yet. I'm not too confident with the metal strap idea (not that it wouldn't work. Just that I'm not sure how I'd actually physically do it, I'm going to check Bunnings tonight to see if they have something I can use as my brother said he thinks he has seen a similar idea to the straps at Bunnings before).

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Can anyone see any serious problems with this design? My wife is worried that the doors might be heavy considering I'm making their frame out of wood. However I didn't think they would be too bad.

I will be leaving the internal walls of the lock up with the studs exposed, but was thinking of putting a coat of paint on both the outside and inside walls to just seal it up a bit and avoid anyone having direct contact with the timber (they say the treatment is safe to touch but would feel more comfortable knowing I can't touch the timber).

[ringtail]

Chemset kicks ass. Basically, drill the hole in the stump, clean the hole out ( vital this is done) squirt the chemical epxoy into the hole and slide and piece of threaded rod into the goo. Wait for it to go off, drill a hole in the timber, slide it over the threaded rod, nut and washer - done. A few differernt brands out there, but Sika make a pretty user friendly one - use a standard caulking gun, fix the mixer nozzle onto the Sikafix cartridge squirt it out onto a piece of scrap until a nice fully mixed product is coming out. Then you stick the nozzle into the hole as far as it can go and slowly fill it up pulling the nozzle back as you go. No expansion problems at all and the end result is very strong and permanant. You buy the threaded studs in whatever length you need. Bunnings sell it all.

[jago]

Dont buy the chemset guns they're $80 use the glass vials that slide into the hole and you crack with the reo...a lot cheaper.

[deltoid]

I'm going to Bunnings tonight to price everything so I will have a look at that Chemset stuff.

I've got 3 concrete stumps to deal with (which means 12 anchor points).

One of the stumps is a steel peer which I'm just going to drill through and thread a bolt through the hole.

[ringtail]

Ive never used the glass vials jago, do they go ok ? The big chemset guns are great (a) if they are someone elses (b) you have a lot of holes to fill. Thats why I like the sika product, standard gun and even if you throw half the cartridge away its only ten bucks in the bin - which I reckon is fine if you dont use it very often.

[deltoid]

Ive never used the glass vials jago, do they go ok ? The big chemset guns are great (a) if they are someone elses (b) you have a lot of holes to fill. Thats why I like the sika product, standard gun and even if you throw half the cartridge away its only ten bucks in the bin - which I reckon is fine if you dont use it very often.

I went to Bunnings. They had the little glass tubes however it was $30 for 10. Whereas I can get the Chemset 101 kit which has 2 x 380ml canisters for $58.

Sometime between now and Christmas I will be fencing in underneath the house and will need to put more anchors in stumps for the fencing so I figured getting more will do the trick. So I think I'll just get that.

Can I just use a regular caulking gun or do they make it so that only their gun will work? There website says for use with their gun but I'm not sure if that is just marketing. http://www.itwproline.com.au/Chemset-Injection-System/default.aspx

[ringtail]

The 101 is for the large purpose built gun only. They are pretty pricey. The beauty of the 101 system is the cannister has the tap on it . Once the sika product is open you must use it

http://www.sika.com.au/cmc/Datasheets/tds/SikaAnchorfix1_tds.pdf

[deltoid]

Thanks Ringtail. Do you know somewhere which sells it? I looked for alternatives to Chemset whilst at Bunnings but didn't see anything.

I think the the Chemset gun is $85 at Bunnings which makes it quite pricey to get the kit. Even though I will be needing to do a fair few holes later (approx 72 anchor points needed when I do the fencing).

[ringtail]

Most building supplies companies will sell the sika in their hardware sections, however if you have 72 holes to do, I would go the chemset and the special gun. When you work it out you should be infront as opposed to using the sika, which is best for small one off type jobs. Dont forget, no matter which chemical type product is used, it is vital that the holes are clean first - compressed air is easily the best option for doing this.( safety glasses and mask)

[jago]

I dont use Bunnings beacuse I have a good builders merchant and they charged me $2.20 each for the vials ,(ringtail) the worked really well for the starter bars that I forgot to put in the slab on the retaining wall:doh:

The vial systems is for one off small applications I had 10 holes... perfect, if you're going to do 72 I would seriously look at Chemset Gun it works out a couple of bucks per hole and you will have the right equipment to do the jobs correctly.

[deltoid]

Yeah, I guess once I take into account all the other holes I need to do, the bigger set and gun probably make sense.

[ringtail]

Just got back from my timber supplier and I priced the ramset gun at $ 77 including the G . Ramset now do a smaller tube ( like sika) and its $ 33 with the G.

[deltoid]

Just got back from my timber supplier and I priced the ramset gun at $ 77 including the G . Ramset now do a smaller tube ( like sika) and its $ 33 with the G.

Thanks for that, I will see if Bunnings have it. Unfortunately most of the places around me are closed on the weekend so Bunnings is my only option (at least that I know of)

[ringtail]

where abouts in bris are you ?

[deltoid]

Virginia.

[ringtail]

Home (http://www.virginiabuilding.com.au/)

Ive been there once when I was doing a job at shorncliffe - seem ok

[deltoid]

Home (http://www.virginiabuilding.com.au/)

Ive been there once when I was doing a job at shorncliffe - seem ok

I tried that hardware on Saturday. I'm glad you pointed them out at as they aren't too far away so makes things easier.

I grabbed some Ultrabond 300 from them. It loads straight into a caulking gun. I also bought 2.7m threaded galv rod. I cut it down to the sizes I want for the anchors and went to work.

I broke two caulking guns (admittedly they were cheap ones). Unfortunately though without a 3rd caulking gun the chemical went hard in the nozzle so that was one nozzle down.

So I went and bought a better caulking gun the following day and tried again. I got 2 anchors into a stump. Then I put the gun down for about 2minutes whilst I played with the anchors to make sure they were set properly. Picked up the gun again and went to do the next stump......no good. The chemical had gone hard in the nozzle.

It was pretty devastating.

So what can I do to stop this happening again in the future? My wife thinks it is because I didn't plug the hole at the end of the nozzle when I put it down. However I cut some away off the nozzle and it had gone hard somewhere higher up.

At the moment, I'm thinking I just bite the bullet and pay the $145 for the Chemset 101 kit and gun and hope it is more user friendly.

[ringtail]

Bugger. 2 mins in chemset land is a very long time. Basically, you have to be ready to rock, fast. All holes drilled and clean, all the studs ready and go for it. Once the hole is filled, push the stud in gently with a scew motion and leave it. Dont touch it at all. Excess goo can be chipped off after its set. Really helps to have 2 people sometimes. One filling the holes and one placing the studs. The chemset gun is a better, but time is still the enemy. You will still need a handfull of nozzles. It doesnt matter if the studs droop a bit in the holes. You just drill a bigger hole in the timber stud and use a 50 mm square gal washer, which you should be using anyway.

[Bedford]

At the moment, I'm thinking I just bite the bullet and pay the $145 for the Chemset 101 kit and gun and hope it is more user friendly.
I don't think this will be any better, my son has one and has had the same trouble as you.

What Ringtail said is the way to go. :)

[deltoid]

thanks guys, that makes me feel better that I'm not the only one who has done that.

I might get my wife to be ready with the anchors or working the gun next time and get it done quicker.

Thanks guys. :) I don't know where I'd be without all your help

[deltoid]

Well, I gave it another crack this weekend just past and had more success. I bought a tube of the Sika's branded one for $20 from Bunnings. I had my wife working the gun and I set the rods.

Got them all in without trouble this time.

I've built one wall so far (been slow progress as I keep having interruptions). I'm hoping to have both days this weekend free so should get a lot done.

My main point of contention at the moment is whether or not to use stirrups on all the walls. All the walls are raised off the ground about 8cm. I've put one wall in place and it is in quite solid however I worry that if I one day put shelves on the walls the weight could make the wall sag. So I was thinking of putting a single stirrup in the middle of each wall to help avoid sagging. Just they might be a bit tricky to get into place.

Are the stirrups a good idea or is there another way?

[deltoid]

Hey, sorry guys, I have another question.

I've got 3 walls up so far. Now I'm up to building the doors and hit a bit of a cross roads.

I've attached two pictures with the two different ways I'm looking at going about it.

I'm building the doors out of T2 MGP10 timber 70x35mm. I'm trying to avoid sagging.

Option 1: I've made the doorway smaller 1.8m and used stirrups to hold the small stud walls up. It will result in a smaller doorway which at 1.8m is still pretty large but having the whole wall a door would allow for more space moving things around.
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Option 2: I've made the doorway wider, however due to each door being almost a square I'm a bit worried about sagging. I wasn't sure how to go about doing a door of this shape, so I decided I'd build each door like I would a normal stud wall, then run a diagonal beam from the two opposing corners. In order to fit the studs, noggins and brace beam all within the frame, I was going to offset each of them 90degrees to the outside of the frame (So the stud + brace would be 35mm + 35mm = 70mm thick, the same as the outside of the frame). Hopefully I made some sense with all that.
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Which way would be a smarter way to go?

[Bedford]

I think you could go either way, as long as you've got the braces it shouldn't sag.

What I would do though (and this may just be how you've drawn it) is lower the bottom hinge so the brace is pushing more directly on it.:)

[deltoid]

I think you could go either way, as long as you've got the braces it shouldn't sag.

What I would do though (and this may just be how you've drawn it) is lower the bottom hinge so the brace is pushing more directly on it.:)

I was planning on putting the hinges 30cm from the top and 30cm from the bottom. I've not done this before so feel free to point out if I'm wrong with that thinking.

I might go with option 2 then. Is there anything I should know about the bracing? Do I just run it from one corner to the other (with the low corner being the side which has the hinges).

[Bedford]

Is there anything I should know about the bracing? Do I just run it from one corner to the other (with the low corner being the side which has the hinges).
The bracing needs to be a tight fit so when the weight comes on it the door still stays square, if there is any slack in it the door will drop at the opposite side to the hinge.

I would still lower the bottom hinge more in line with the brace, maybe come up 100mm then fit hinge above that.

[deltoid]

The bracing needs to be a tight fit so when the weight comes on it the door still stays square, if there is any slack in it the door will drop at the opposite side to the hinge.

I would still lower the bottom hinge more in line with the brace, maybe come up 100mm then fit hinge above that.

What if I built the door like a normal stud wall, then laid the brace across it and just nailed it on to the outside of the wall. Or is it better to have the brace within the frame itself rather than nailed onto the outside of it.

[Bedford]

It's better checked in, that way the load is in compression of the brace and not just relying on the nails.

[ringtail]

Depends on the look you are after. Brace on the outside is more of a barn door look, while having the brace as part of the frame will let you line the door with whatever you like. If the brace goes on the outside you will have to line the door first then add the brace. Definitely move the lower hinge as low as you can.

[deltoid]

Thanks guys, I really appreciate all the help you have been giving me.

I will put the brace inside the frame. I'm going to line the outside of the lockup, but I was planning on leaving the studs exposed on the inside.

Now I have that problem sorted. I have another bracing question.

For the other 3 walls, they are all suspended between the two stumps. They are solid and holding fine (I haven't nailed them into place yet, they are just being held there with clamps).

Originally I was planning on putting a single stirrup in the middle of each wall to help prevent sagging. However, I don't really want to use stirrups if I can help it as I don't think the slab is very thick (maybe 10cm) so I think I might have trouble dynabolting / chemically anchoring into it.

So for those walls I have.

Option 1: Put a single stirrup in the centre of each wall to prevent sagging.
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Option 2: Use two diagonal braces, nailed to the inside of the wall (it would be outside the stud frame, alternatively I could chizel sections out of the studs to fit the diagonal brace within the wall. Or I could cut the diagonal brace into sections and put a different brace section between each stud section.
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[Bedford]

However, I don't really want to use stirrups if I can help it as I don't think the slab is very thick (maybe 10cm) so I think I might have trouble dynabolting / chemically anchoring into it.
Use a stirrup and 50mm x10mm dynabolts, it's in compression and not going anywhere, much simpler than all the bracing.

[deltoid]

Use a stirrup and 50mm x10mm dynabolts, it's in compression and not going anywhere, much simpler than all the bracing.

Neat, I'll give that a go.

Thanks again, guys. Usually I'd ask my dad these kinds of questions but my folks are overseas visiting family for a month or two so I don't have anyone to get advice from, so I really appreciate your help :2tsup: