Been a while since I was here, the drive took a back seat over the winter! Still I have now finished my edge courses and my sub-base (40MM limestone crusher run) is compacted to levels. (and all the rain we just had shows that my falls are right! )
So I have a week off to lay the block on my bedding sand. As this is a big area, I'll need to use trammell bars to get the screed depth right. I just re-read the bit on getting the screed level right and will be building a test level first thing on Saturday.....
But what is not clear to me is how the tramell bars are fixed into position on the sub-base. If I use metal poles, how are these held in place? If I use timber, do I just hammer nails through em into the sub base? It is clear that the bars should not move, but how can you achieve that without leaving damage in the sub-base? And these need to be removed easily after screeding? Help!
(If it's of any significance, the area being paved is about 12M x 14M that is trapezoidal in shape and slopes toward the house down the short side. I'll be screeding along the short side down the slope and paving up the slope from the long side)
The trammel bars (screed rails) simply sit on the sub-base (or the sand laying course). They are not fixed in place - you simply rely on their weight and the surrounding sand to keep them in place while you complete the screeding, whereupon they are lifted out and set aside for re-use.
Thanks for the update. Luckily I saw some photos of tramel bars in use and the penny dropped! I used 100x25 mm planed planks buried in the bedding sand weighted with some bricks, the width of the planks meant that thay did not sink or move.
I have not been checking on here over the last week as I was busy actually DOING the drive! The last block was laid last night at 9:45 PM and The final check for dips and peaks will be done tonight (run out of holiday time) followed by the jointing sand. It does look good.
)