Thank you for your enquiry. The type of anti-rot products referred to are “Metalex” and similar. They are copper or calcium naphthenates which stop the curing process where the Builders Bog contacts them. Earles wood hardener sounds different, though I cannot get it in New Zealand where we manufacture, so I have not checked it out. The beam is structural, I presume, and if there is so much rotted, papery timber that you cannot remove it all and bond the Builders Bog to remaining solid timber, I would be concerned about structural integrity.

Builders Bog should only be used for cosmetic and weathering purposes. It will not impart new strength to a beam. Nor can Earles hardener, I am sure. It looks to be a water-based product from their web page. Even epoxies will not give tensile strength to to underside (tension side) of a beam, unless carbon fibre or similar is bonded on as well. The area size is not a problem, and we have used up to 12 litres in single repairs ourselves. But only for non-structural window frames and sills etc. Don’t hesitate to ask further questions of us if you need to.

Regards
Stuart Jordan
Managing Director

Thank you for your reply and advice, we purchased the large tin, 1L I think. Patch the builder bog in. The first batch dried too quickly, so we use less of the hardener. Overall, everything went well. We also bolted in another beam onto the no rotted timber. The only trouble is that the bogged area have some cracks, ranging from hairline to about 2mm, not sure why. Should be buy some more builder bog to cover the cracks or just sand and paint?

Kind Regards,
Peter

I am a bit concerned about the cracks. Builders Bog will never crack due to shrinkage. Are you sure your rotten beam has not flexed with the load on it and stretched the filled area? Remember, in a normal beam the top is under compression (ie the opposite of stretching) and the bottom is under tension (ie stretching). Did you jack up the rotten beam a bit to take out any sag before bolting the new one to it, to ensure the load is being taken mostly on the new beam? Did this cause the cracking – if and when the jack was released? I have no other explanation. You can certainly refill the cracks, but I would want to be sure they have not been caused by excessive load and stretching of the old beam.

Regards
Stuart Jordan
Managing Director

Once again, thank you very much for your prompt reply. Wish companies in Australia are like you guys, Great work. These are the steps we’ve taken.

1. Removed as much rots as possible and let it aired.
2. Jacked up the top decking timber and put the new supporting beam flushed against the side and top of the existing beam.
3. Put in the bolts and remove the jacks.
4. Spray in the timber treatments as per previous email and let it air for about 2 weeks.
5. Check for any rots and remove any loose debris.
6. Filled the gaps, rotted timber, with builder’s bog and let it dry for about 2 days.
7. The fill looks dried but still feel little like hard plastic, can push little in and can still smell the bog.
8. I did jumped, oops, on the top timber a few days later, to test if the new beam and bogs are good as we will have some guess coming over. 9. My wife notice the small cracks the day after and i notice the bog are not not flushed against the timber by about 1mm. Could be from the flex of the timber as we had some rain and then some hot days. So, not really sure what to do next. The cracks has settled and seems to stay the same size. Maybe should jump on it little more before our next bogging.

Please advice.

Kind Regards,
Peter

I am sorry for the delay in answering, but I injured my back and could not get to a computer. The Builders Bog should be about as hard as pine timber when cured and should remain flush with the timber unless the timber has moved for some reason after it was filled and sanded flush. 1 mm is a lot of movement. From memory, you used Earles wood hardener on the rot – I do not have your original email here at home.

We are not familiar with that product. Is it possible the Builders Bog did not adhere to it and has come loose? In any event, it sounds like you did a good strong repair, and I would now make sure the existing filler is stuck to the hardened wood and then just apply more on top, if it is, and sand flush. If it is not stuck then you will have to lever it free (it will come away in a lump if not stuck) and use a different type of filler (not a polyester one like Builders Bog), but this sounds unlikely to me. It is an odd problem, an I hope this information helps

Regards
Stuart Jordan
Managing Director