Ant infestation around my window frame - what do I do next

[roofmog]

After a recent ant infestation around my windows I decided it might be good idea to remove the window frame and see if there was any damage to the brickwork. It does look as if the ants had been tucking in to the fabric of the building. Having treated the infestation I am planning to repair the damage with mortar. However, a couple of other issues have arisen. On closer inspection I have realised that the slightly loose second brick up from the sill is actually a block of wood rather than a brick. Not sure why. I discovered something similar previously when one of the damaged bricks at the bottom corner of a door frame turned out to be a block of wood that had rotted away. Before I replace the block by the window I just wanted to check that there is no legitimate reason for this being wood rather than brick.

Also the wooden frames appear to have been deliberately prevented from coming into contact with the brickwork. As can be seen in the picture, there is quite a gap between the window frame and the brickwork, would there be anything to gain by filling this with sealant etc, or does the air gap help to preserve the wood. The windows are about 20 years old but there is no sign of rotting. Also although the sill frame was screwed into the brickwork plastic spacers had been used to create a gap of about 20mm between the wood and brick. Is there a technical reason for this, or was it just to create a particular sized aperture for the window opening?

 

[Gazman16]

The wooden blocks were most likely either:
1. Horns from the original windows or
2. Fixing blocks that the original windows were nailed to.

The gap would be for fitting reasons (being able to get the windows in) and to prevent moisture from the walls soaking into the windows.You could put some DPC up the edge of the window and then fill the gap with expanding foam.

 

[roofmog]

As you suggest, the block of wood was probably a fixing block for the old windows as there is another one in the same place on the other side of the frame. They are both a bit decayed and loose so not playing any structural support role. I was thinking of removing them and filling the gap with concrete.

 

[roofmog]

Returning to this project after a break. The wooden blocks were loose and starting to rot so I have removed them. Because of the rot they were not bearing any load, but I now don't know what to replace them with. They were the size of a full brick (old type). Given the narrowness of the gap a brick would have to be fitted in I cant see how it could be mortared in properly without removing some plaster work, which I am reluctant to do. I suppose I could replace them with another wooden block but presumably this would eventually start to rot again. Alternatively I could just fill the gap with concrete although I'm not sure that this would be best. Any thoughts/suggestions welcome please.

 

[Dextraneous]

Fairly dry-ish 3 sand:1 cement sharp sand mortar mix will be fine. Stop worrying and over thinking things.