Filling oak frame gaps

[Smudger]

Hi all, first post here having just moved in to new home.

We are in an 1860s property that has had a oak framed conservatory fitted around 20 yrs ago. From looking at other posts in this forum I understand that the green oak frame should by now have dried out a bit and gaps should now start to settle down.

Previous owners had filled gaps with clear silicon, which was no longer attached to oak so i have now totally removed all traces (not using silicon eater!). I now have nice gaps to outside providing additional unwanted ventilation.

Pictures attached to give idea of problem, please suggest if possible suitable filler to match colour as near as possible - totally understand i wont get exact match .

Thanks.

 

[Cubist]

You will need a supply of oakum and caulking cotton together with lime mortar and filler. Caulking cotton is a dry material used for narrower gaps of up to 5mm and is twisted and braided as it's pushed and hammered into the joints. Oakum is jute (typically) soaked in Stockholm Tar (a light oil) that again can be braided and twisted as needed and then pushed and hammered into wider joints between the timbers. Note: the oil will bleed out the oakum as it is hammered into place and will stain the timbers, you will probably need to then oil the faces of the timbers to blend the colours. A shallow channel should be left above the cotton/oakum and this should be filled with either a lime mortar or a lime filler - particularly outdoors; beards like to steal it during nesting season. Done properly you will only ever need to re-visit the caulking to replace any lost mortar/filler. Such losses are almost inevitable as the timbers expand and contract.

 

[Smudger]

Thanks Cubist,

As I'm totally new to this please bear with me, i understand the oakum use but the lime mortar i dont understand for internal use in gaps between timbers as opposed to timber / masonry gaps.

Does the lime mortar take on the oil and therefore blend to match the existing wood.

Could you point me in the direction of suppliers for oakum etc.

Thanks

 

[Kearn]

Rose of Jericho are my go to for Oakum. If you’re anywhere near Wiltshire, you’re welcome to some as I have quite a bit spare as it comes by the KG! Although you may get through a KG …

Technically there’s no need to fill the internal gaps with lime. And you won’t make a mess in doing so, as lime discolours oak and neatly filling gaps like that is a serious pain. It’s an aesthetic choice inside.

If it were me, I’d just deal with the outer 50% - oakum plus sacrificial lime fillet. Whatever you do internally is likely to draw more attention to the gaps than leaving them as shadows.

As for your green oak, it will have finished drying out and shrinking a long time ago. You will get seasonal movement as the oak swells with the seasons, so flexible is key.

 

[Cubist]

It's really for the final finish appearance. Oakum can look black when packed into place and some of the oil will bleed into any mortar of filler used as a closing fillet. Outdoors here I usually paint the seams with a little whitewash - the house is a Tudor Black and White. Internally I have used a milk chocolate emulsion paint on both any mortar or filler I may have used and have also used it directly over the caulking cotton - its a fairly good match to raw oak.

I typically but oakum and caulking cotton from the outfit below but eBay is a good source for smaller quantities.

Oakum Docka- 4 kg pack - Classic Marine

Best navy oakum, steeped in stockholm tar. Best navy oakum, steeped in stockholm tar. Generally used for caulking below the waterline. 1 x 4kg pack. 9 inches high, diameter of 10 inches , reels off from the outside. Oakum is natural hemp that has been impregnated with stockholm tar (pine…

classic-marine.co.uk

 

[Kearn]

A shallow channel should be left above the cotton/oakum and this should be filled with either a lime mortar or a lime filler - particularly outdoors; beards like to steal it during nesting season.

it will take more than a bit of lime to deter those Beards once the winter hibernation comes and they can no longer live in their local coffee shop in flannel shirts…

 

[Smudger]

Thanks everyone for your prompt and useful replies.

I'll get some Oakum and see how i go from there.

 

[Smudger]

Cubist
You mentioned about using a light oil on the oak, what would be best to use?

Thanks

 

[Gothichome]

I think I would get an oak board and cut myself some fill spacers and glue in place, then stain to match.

 

[Smudger]

Ok, thats interesting, thanks