Thread: milling for overlay/strip blackwood floor

What happens if you find a house with a standard wooden floor. I would not resaw until you know what you have the need for.

When you finally mill the boards before installing the boards should be store in the room they will be laid for at least a week and preferably 3.

Originally Posted by BobL

What happens if you find a house with a standard wooden floor. I would not resaw until you know what you have the need for.

Yeah, purchasing a house of yet unknown construction is a posibility but unlikely, most likely it will be the renovation scenerio as its a "house on farmland / inheritence" issue. But I understand what your saying.

The Macrocarpa logs I dropped last year I'm planning on milling in a couple of months time but I'm just squaring them into large cants about 12" x 12" or bigger & I'll stack then in the shed to dry overtime, then I'll resaw them at a later date when I know what dimensions I'll require. I'm not game to do this with blackwood because unlike cypress, blackwood will end check severly.

cheers,
Dean

The mill i worked in cut lots of overlay.All hard wood thou.
We would go for 100x40mm cants to be sesawn after kiln drying.We also got 18mm recovery.
Dont now mutch after that but aparently they got 3 12mm overlay out of a 40-45mm cant.

Hi Sprat-Tech,

You are generally going in the correct direction with your plan A. Blackwood is very easy to dry satisfactorily and comes up OK with air drying only if done in the correct location.

There is practically no collapse on drying with Black Wood so if you can saw accurately then I'd say allow 20mm in green thickness for overlay flooring and 20mm extra in width to allow for a bit of spring on drying.

I wouldn't dry this thickness in a shed or house. Efficient drying is a function largely of air movement and there's not much of that indoors. I'd go for a stack in the open with the end pointed into the prevailing wind and a cover of roofing iron that overlaps the stack by about 250mm each side/ each end. Essential that you don't rack with green rack strips with Black Wood or you can end with sticker marks clean through the timber in material up to 50mm thick usually in a contrasting red color.

There's not much value in rough thicknessing the boards before taking them to a business with a moulder to get them finished unless you want to fault dock them after the initial dressing but generally the longer the sections for moulding the cheaper is the job.

If the boards are only 2 to 4 feet long you will need to have them end-matched as well. You could do this with a Domino or a Biscuit Joiner but that;'s a pretty tedious task. I guess it's not essential to T & G boards that are to be bonded to a concrete floor. If you don't go for the T & G then you will need to be fastidious about applying the adhesive and rejecting or shortening bowed boards to avoid a drummy floor. Make sure you use an elastomeric adhesive formulated for the job that will allow of some timber movement down the track not the cheap rubbish to be found around the place. Again make sure the slab has a first class moisture barrier without punctures or gaps and that the concrete is allowed at least 6 months to cure before laying the floor.

It's a lot easier to avoid problems with timber flooring by not laying it where it probably won't perform well in service than trying to invent solutions to manage the impossible


Good Luck Old Pete

Originally Posted by spray-tech

Slowly making improvements to the homemade mill, I had trouble cutting consistant board thickness using a hand winch for lowering the cutting head. I've now fitted a magnetic ruler scale & a more precise 12 winch, the mill now cuts to the milimeter

In a couple of years time I planning on either renovating an existing home or building a post & beam timber cottage, but cant predict yet due to circumstanses. However in either case I'll have a cement floor as a base. This means I can use the timber strip overlay method.

I have access to plenty of blackwood logs but many are on the smaller size & I want to make the most efficent use off it.

If the dried & finished timber to go on the slab is 12mm thick, how many millimeters thickness should I mill the planks? also if the finished timber is 80mm wide, how wide do i mill to?

Please correct me if you think the steps below are not a good way to go or can be improved upon -
1. I will mill the logs into planks
2. I will sticker and dry the timber in a shed for a couple of years (could even do this in spare room in house to aclimatise)
3. I will do partial thicknessing and basic edging of planks once dry to remove any cupping. bows & bends
4. I will take planks to a profesional timber machinist for the final finishing on a 4 head plane
5. Ready to install?
What about tounge & grooving, do i need it? the board dimensions I'm considering are width 80mm or 100mm, thickness 12mm, lenght between 2 to 4 feet vairiable.

here's a pic of a few boards cut from a couple of crappy blackwood logs that I am testing the mill on (wont be used in flooring a, degraded a little), notice the vairation in board thickness on the stickered one, this is now fixed

thanks,
Dean

Dean

The placing of boards in a room prior to laying them down is for acclimatisation purposes only and not for drying. There would be insufficient air flow in a room for a significant quantity of boards. The reference Bob makes is correct but it equalises the moisture content of the boards to that of the room. For example you may have boards dried to 12%MC, but you may live in a humid area. The boards will re-absorb to the moisture of the region.

The 12mm thickness you are talking about would normally be used for wall lining boards. 19mm is more common for flooring. I appreciate you are using it as an overlay. Others may care to comment about fixing direct to concrete (gluing?) or on top of battens. I would lean towards the latter in which case I would definitely go to 19 -20mm thick boards. You would probably have to cut them around 26-27mm thick to allow wastage in drying and machining.

I don't know the shrinkage rate for Blackwood, but if nobody else has posted it, I will look it up when I am back home.

I would certainly go for a tongue and groove flooring profile.

Regards
Paul

Thanks guys, I sense you are giving me very good direction here!

Clearly, the 1st step even before I put a log on the mill is to go and see in person the tradesman who I'll get to do the final dressing of the timber as I may be doing something superfluous that they can do much easier.

I forgot to mention in my original post, the cement slab in the "to renovate" house is about 18" thick & poured about 30 years ago, it has coiled poly pipe for hydronic heating, so would probably remain drier than a lot of slabs. I should discuss with a builder or 2 whether to use glue or raise the floor with small batterns, there's a variety of issues to consider.

An advantage with renovating vs a new build is I can do this over time since I'm removing old carpet & can do it room by room or as I have timber available & ready to use, a new build would mean it has to all be done at once.

The drying process, OK I need more air movement. I have another shed thats bigger & used for farm machinery, roofs higher, part of back wall on the north is missing (never finished it), very breezy & level cement floor, I'll use it, problem solved.

I haven't much experience in drying timber. I can imagine dark stickers easily staining pale timber but what about the reverse?, would dry Cypress Macrocarpa be OK for stickers? or should I use blackwood? I have a stack of ordinary quality 8" x 2" blackwood about 6 years dry that I can cut up for stickers?

cheers,
Dean.

Dean

Placing your drying stack in a shed that has good airflow would be excellent. I should think the old blackwood cut to sticker size would be excellent too. I looked up Blackwood in Bootle's book. You're in luck there too as it apparantly dries easily without degrade and shrinkage is small (1.5% radial and 4% tangential).

This means that if your saw is performing well you may be able to mill the boards at say 25mm to end up with a seasoned and dressed board of 19mm. I would consult with your tradie to get some recommendations for the floor thickness.

Your concrete slab at 18" (450mm) is interesting, a monster even. Is the heating still operational?

Regards
Paul

Originally Posted by Bushmiller

Your concrete slab at 18" (450mm) is interesting, a monster even. Is the heating still operational?

Regards
Paul

It was made thick because it supports double brick and there's a lot of clay underneath, I was only a little kid at the time but I rember tradies coming from melbourne to pour it & their workmanship was 1st class, not a puddle after it rained.
Yes the hydroponic heating still works, I remember when it was installed the heating oil (similar to diesel) was only 11 cent per litre, 10 years ago the folks had a gas burner installed when gas was cheap.
I'm very interested in building a masonary heater sometimes called a russian stove in the living area as we have a good supply of firewood. the heater could also be plumbed for water to run the underfloor system.

cheers,
Dean.

Dean

It sounds as if you could run a combination of wood fired and, say, solar to give you under floor heating.

However the reason I asked was that placing the timber floor over the top will affect hoe the heating performs. I would expect that the insulating properties of the timber will make the underfloor heating less effective.

Just something to be aware of.

Regards
Paul

However the reason I asked was that placing the timber floor over the top will affect hoe the heating performs. I would expect that the insulating properties of the timber will make the underfloor heating less effective.

Thats exactly right Paul, Its a bit of a dilema when replacing old carpet, what do I replace it with?
1.new carpet is out of the question, simply don't like it.
2.Ceramic tiles have a place especialy kitchen, bathroom, surounding heater, etc.
3.Timber flooring has the natural aesthetic appeal that no other product can equal, in my opinion. So it will probably be a combination of timber & tiles, practicaly & aestheticly they should compliment each other if done correctly.

One reason I'm favouring 12mm boards directly onto the concrete (including moisture layer), over battens with 19mm boards is there would be greater thermal conductivity, I feel we need to eliminating the air space associated with using battens as its an insulation layer in itself. Also a dense timber should be more conductive than a softwood like pine which has a lot of air in it, another reason why I'm choosing blackwood.

With using timber on a heated floor there's no question it will lower thermal effiiency but it can be minimised, tiles would be the most efficient, lets remember carpet has insulation properties too, so therefor a mix of timber & tiles may simply equal the existing carpet. theres a lot of other areas of the house that are poorly insulated through lack of design, adress these and there will certainly be a significant net gain in energy/heating efficiency.

cheers,
Dean.

G'day.
80x12mm T&G overlay is cut 108x20mm.
You can direct stick to the slab with Selleys Direct stick adhesive with their VBS slab sealer.

Overlay 12mm is too thin to go over battens @ 450 centres. You can lay plywood and glue and nail to that.
A heated substrate will cause futher drying of the timber once it is insitu. this will show as gaps between the boards.
MC% for heated slabs with Hardwood T&G requires a 8% MC.
Your underfloor heating will still work fine through the timber. this is why you need 8%MC.

We have supplied a lot of floors used on heated slabs and this is what we dry to.

i would only try and dry timber in a shed if it had a roof and no walls as said before you need air flow speaking from expereience i stacked some cypress which i milled in a shed which was open fronted and did not dry

Hi Tlbsq,

Spot on there. The physics of timber drying is well known. In a stickered stack the moisture migrates from the timber to the surface of the boards where it evaporates to form a high humidity layer of air between the layers of boards. Without air movement the stack forms its own stable high humidity micro climate and the rate of evaporation is then severely restricted and drying slows to a crawl. Bring on the air movement and the high humidity air is removed ready to be replaced with another and so it goes.

It's not all a negative and it's an attribute that can be used to slow down drying of products such as drying indoors big black wood squares for turning to avoid checking on the back sawn face as just one example that is practiced over here in Tassie.

In well managed drying yards its common practice to shelter the appearance grade timber with stacks of structural grade timber placed up wind of the good stuff, likewise its good practice to point the ends of appearance grade stacks into the prevailing wind direction to slow the wind velocity through the stack if slowing the rate of drying to optimize quality of the dried timber is required.

It's a fascinating topic is timber drying and there's an awful lot already known about successfully drying many species. I don't know what it's like up your way a lot of folk here insist on re-inventing the wheel and re- learning it all over again by trial and error. More often than not they don't keep any climate and time records of what they did so when it goes well they don;t know why so they can't repeat the process and when it goes badly they generally find something else to blame and its usually the quality of the logs that get the ticket.

It's easy to identify those folks.....they are always claiming to have THE SECRET!!!!! it's either a secret kiln schedule or a secret kiln design or some secret black magic they have discovered that they can't tell you about. I give the lot of them a wide berth just in case its rubs off on to me,


Cheers Old Pete

Originally Posted by tlbsg

i would only try and dry timber in a shed if it had a roof and no walls as said before you need air flow speaking from expereience i stacked some cypress which i milled in a shed which was open fronted and did not dry