Intergrain DWD on Merbau Deck

Hi all

We are in the process of building a deck with Merbau floorboards (and an insulated roof).

Regarding coating the Merbau, the builder has suggested we put DWD onto it straight away, and not to worry about the Intergrain Dimension 4 pretreatment. However after reading all the comments here, and how it is recommended to let the Merbau weather, I am not too sure about what the builder is saying now ..

Should I be following the builders recommendations ? I would have thought they wouldnt suggest something that could be detrimental to the finish of the deck, and they have done nothing for me not to trust what they are saying - just this is getting to me a little :) I wouldnt expect there could be much weathering to be done with a roof over the top.

Dear Biffo,

Welcome to the forum and I am certain you will find it a wealth of information to sift through most of it based on other peoples experience. With regards to deck coatings there are quite a large number of products out there all offering a good initial finish at the begining. From what it sounds like your deck has good coverage from the elements. In saying that there are very few decks that I see that are different from this. The timber up close to the house looks great several years after it was laid but all along the outer edges is starting to fail. It is either grey-black or peeling or just stuffed. The greatest destroyer of all external timber is sun(uv) and moisture. What generally happens on decks like the one you are having built is the edges go off quickly and before you know what is happening the zone between the good and the bad gets past where you can recoat and have it look the same. Intergrain DWD is probably one of the coatings that I come across more often than most and it generally breaks up and looks like #^&$@. I have a attempted to remove it by using a chemical stripper and high pressure water blaster which generates a huge mess of old coating going everywhere and by sanding. Then sanding can be a hassle if your deck builder uses dome headed nails. That is another story that has been discussed on this forum many times. The other issue is merbau is a very oily-tannin filled timber. Most manufacturers of deck coatings recommend waiting 3-4 months minimum before coating as the timber MAY bleed some of the oil-tannin to the surface and ruin the coating. Now one of the best weathering methods is to have it rain on the deck weekly over that time or hose it weekly to draw up the oil-tannin, however, with level 5 water restrictions that is completely out of the question. If you just left the deck for say 4 months to maybe bleed some of the oils that might be a happy compromise. Most people once they have the deck built want it to look its bestASAP. In this entire story-debate-fingers crossed discussion of decking you will find enormous differences of opinion,ideas and suggestions. I have found it two steps forward and one step back. I am sure that many others on the forum will add to your question and then it is a matter of sifting through the information and going forward armed with as much knowledge as you can gain. Don't be afraid of letting it sit for 4 months or so. It is very easy to clean and bring it back to beautiful wood before coating. Please do not sit any pot plants directly without the 4 little feet, BBQ cylinders or any metal steel objects on the deck or you will wind up with nearly impossible black marks to get out. I have been using Flood Spa&Deck which is a water baed acyrilic on the decks that I restore. I hope I have given you some food for thought.

Good luck,

Jim J www.restore-a-deck.com.au

Just coat it in tongue oil, crack open a beer and enjoy. :D

If you want to maintain the features of the timber , then a deck oil is the go or their is soon to be on the market a water based polyurathane that is able to be put on decks and is uv resistent . But if you want the effect that dwd will give you then it is most impeerative that you coat it with demision 4 first. Do not use a roller but use a lambs wool applicator . I am doing a series of decks (7) at 400 m2 each, We have tested intergrain and have rejected it and have gone in favour for the water based product. The difference is outstanding.

Such an array of deck coating methods.

I have been thinking about Merbau decking, I am happy to leave an oiled finished (maybe speaking from ignorance on this point), can these be applied straight way (I was actually thinking of giving the first cost on both sides of the boards before laying them)

Quote:

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Originally Posted by Larry McCully

[...] is soon to be on the market a water based
polyurathane that is able to be put on decks and is uv resistent . [...]

---

What's the product's name and manufacturer?
Is it single-pack or 2-pack?

Quote:

---

Originally Posted by BrissyBrew

I have been thinking about Merbau decking, I am
happy to leave an oiled finished (maybe speaking from ignorance on this point),
can these be applied straight way (I was actually thinking of giving the first coat
on both sides of the boards before laying them)

---

I've written up my experiences previously in this forum - search for a thread
entitled "sanding before oiling", (if I recall correctly).

For a tannin-rich timber like Merbau, if you coat it straight away the tannins
will rise up over time under the combined action of UV and water (hence more
so on areas which are more exposed). Surprisingly quickly, it will look like
crap. Better to let it weather (for an amount of time determined by how much
rain it's getting), then clean with Napisan, then apply oil.

Regarding coating of undersides, if you'll never see them, you might as well
use a more substantial preservative, like stop-rot (the green stuff). Maybe
also an oil-based paint primer as well.

I finished a 20m2 merbau deck recently, and coated it with Spa-n-Deck (as rec'd by some posts on this forum). I left the deck weather for a month, then washed it down with the companion pre-treatment solution, and finished off with 2 coats of Spa-n-deck (ceder). I am very pleased with the way it turned out, and it was really easy to apply.

if you must use an Intergrain product then use ultradeck, not DWD. But I would use Spa-n-Deck.

CHeers

Michael

Dear Tommy C

Great to hear that you are happy with your deck and coating. I have been using Spa&Deck now in my decking restoration business now for the past 18 months and have not had any call backs from customers with complaints of peeling, cracking ,going black or disappearing. What is nice is that Flood is now backing this up with a 2 year guarantee for horizontal and 4 year for vertical surfaces. I do have a problem with Flood's instructions saying that if you have a nice sheen after 2 coats that it is enough. From a personal point of view I don't feel that 2 coats is at all adequate as it really is more like one and a half coats as the first coat is put down on wet timber. I always quote to lay down 3 coats on my customers decks. I do know that when the third coat goes down it really brings it to life and that several other full time restores have found the same. If the deck is in total sun most of the day I recommend 4 coats. I have experimented with 5 but feel it is too much. I do think that 4 gives you three great layers of protection and still lets you see the grain and patterns in the timber. The easy part of this is the coating with the miserable part being the preparation. The two most common questions that I get asked is "how long will it last" and "what is required to redo do . I am absolutely confident that if applied correctly and if the preperation brings the wood back to clean and bare timber you will easily reach the 2 years that Flood is guaranteeing. All it will do over this time is slowly dull with the satin sheen fading but the both the colour and the covering will remain. With your 2 coats at the moment if you feel like adding another coat or two just hose off any dirt, let the deck dry and coat.

If you look at my portfolio in my website all after photos have been completed with spa&deck mainly cedar with several sedona and redwood.


all the best ,

jimj www.restore-a-deck.com.au

Thank you all for the responses! I'm glad I took the time to research because I would have been pretty annoyed to have blown $250 on a tin of DWD to have it look like crap really quickly!

The floor went down yesterday, and overnight we got a spot of rain. I can see now what you all say about the Tannins coming out of the wood! I expected to see something, but not as much as there was!

Can I just clarify - once it gets wet and the tannins show up on the boards, should you clean it off before it dries ?

Dear Biffo,

No please don't worry about the tanin spots. It will not be difficult to clean if you leave it for 3-4 months. The issue is if the wood feels smooth when you rub your finger ACROSS the grain . As long as that feels smooth it will clean easily with either Flood Powerlift which is basically an alkaline wood detergent with the active ingredient being sodium percarbonate or by using a Napisan detergent which is also based on the active ingredient of sodium percarbonate. From my experience all hardwood timbers even in full daily sun can stand up to the elements and still feel smooth after 3-4 months. It will be an easy deck to clean and coat with your choice of product. If you elect to go the napisan way you can buy the no-name napisan. Same active ingredient different perfumes usually half to one third the cost. Mix 50 grams/one litre of WARM water. Spread a liberal amount over wet timber and let stand for 15-20 minutes on COOL timber . You will be amazed at the amount of oil-tanin - dirt sitting on the surface. Scrub and rinse off well. I would then apply a mix of 10% oxalic acid and water for 10-20 minutes scrub and rinse well. You are now ready to coat. If you are using an oil based product you will need to make sure it is dry usually 2-3 days. if using Flood spa&deck you can begin the coating straight away as the first coat goes down on wet wood.

I hope All this makes some sense!

Jim J www.restore-a-deck.com.au

Thanks Jim - it makes plenty of sense!

What do you use to scrub it with ? Do you go for a scrubbing brush ?

Dear Biffo,

Glad the steps make sense. It will work a treat for you. I forgot to add to do the cleaning when the deck surface is cool. It can be a hassle if the wood surface is hot because it will want to dry out on you while you are letting the cleaner sit on the wood surface. As for scrubbing. I am working on decks nearly 6 days a week . I invested in a Rotowash scrubbing machine as it can scrub a lot better than we can by hand and the machine also picks up and gathers the dirt, oil and detergent from the surface. In your case I would just use a fairly stiff scrubbing brush on a pole. Because it is new timber it will scrub easily when you clean the deck. The oxalic acid mixture which is predominantly what most of the deck cleaners on the hardware store shelves will do several things in the process. It will help neutralise the timber surface closer back to a PH7, It will help open the pores of the wood a little which will allow for your coating product to be absorbed a little better. It will also tend to brighten the wood a little more when the timber dries. You won't notice the vast difference with your eyes when using the oxalic acid as you will with the sodium percarbonate. It is more subtle but an important part of the preperation. If using Flood it is labeled as Flood spa&deck prep. Just mix it with warm water and stir it well. I apply both the detergent and the prep with and old pad applicator. I find it spreads both well , gives good uniform coating and is reasonably quick to do. When doing both steps cover an area that you know you can work. You may have to do your deck in several parts.

Good luck

jimj www.restore-a-deck.com.au

Jim

Thank you for your sound advice and information! It definately makes me feel more comfortable about going against what the builder is suggesting.

At the end of the day, I am responsible for the finish of the deck so I am going to make sure it is done properly. Will hopefully win some brownie points with the wife when it all comes together and looks really nice :)

Just another question if you don't mind - I notice the Spa-N-Deck comes in several different colours - are these just stain colours depending on what finish you prefer ? Is "Natural" a colour or is it almost clear so it brings out the natural colour of the timber ?

Also - they advise that on smooth and new surfaces: 35 to 45 sqm per 4 litre can. Does this mean that you can do 2 coats on 35-45sqm with a 4 litre can, 3 coats will require a further 2 litres (so I will need at least 6 litres for a 36sqm deck & 9 steps). Am I reading this correctly ?