IMT3b – Build Part IX

22nd March 2021

Lots of old mastic

Time to prepare the observatory walls to be fixed to the observatory concrete base. Because this observatory had been in place at my last house, we cut the mastic to separate the panels. This left large amounts of mastic on each of the dome segments and on the observatory wall panels. With the use of Stanley knives and an electric sander the job was much quicker than using sandpaper by hand. It still too several hours though.

Sanding down

Then it was a case of placing the wall segments down and biting each pair together running a bead of mastic down each. Now with 2 pairs done, we lined the dome up so that it was at best equidistant from the pier. I then drew a chalk line around the edge, drilled pilot holder where the dome walls would attach to the concrete and then we unbolted and moved the dome walls again.

Dome segments in place

Luke then had the fun of using the SRS drill which is the only drill to get through concrete to the depth needed for the long M8 bolts. Once all were drilled and the anchor bolt sheaths were hammered in, we ran another bead of mastic around the base and then placed the dom walls in their final positions. We then bolted them to the floor and the 2 pairs back to each other with more mastic here too.

Bolting walls together int he dark

By this time it was a getting fairly dark so we tightened up the final set of bolts and called it a night. Luke then spent some time raking the mounds of soil from around the sides and rear of the observatory that use to make up the vegetable patch. The lay of the land means we need to build up one end of the observatory land surrounding the dome by about 6 inches to allow for a flat patio later in the summer.

Levelling the ground for a patio

Finally the day after this I came out early in the morning and ran 2 tubes of silicon mastic around the outside of the observatory so that when I pain on the Rust-Oleum fibreglass Fillcoat waterproofing sealer that it would smoothly go over and not disappear in some of the larger gaps caused by less than professional concrete laying.

Mastic around the dome floor
Hide and Cat 🙂