I've always thought of those titles as the brick house and the lines are clearly there. Talking of which how much of those titles were real and how much was animated? Feels like they may have filmed the fly in but then enhanced the house. The angles were certainly slightly different between the yellow and brick version.
Seeing a shot of the brown house taken from the sky has me wondering whether that might be the day they shot the 1998 titles. You can't actually see bricks painted on the house in any clip of the titles online and it's making me question whether you could in higher quality.
I had to go over to YouTube to check out the titles after seeing your comment Whataday! I see what you mean. However, when I look closely, on the shot where the house balloon before the explosion effect you can see some lines faintly.
It raises a question though; I assumed that the brown was the base and they painted the bricks on top of that, but was the brown the brick colour and the cement lines were painted on?
The bricks are a completely different colour to the brown. In closeup pictures of the brick look you can clearly see it’s a good paint job with different hues in the (reddish) paint which forms the base for the bricks, giving it a realistic appearance. I think it’s just the SD quality of the wide shots in the opening titles that’s washing out the brick effect, as the house in the titles is definitely not the same colour as the interim “brown” house.
It must've been about that time you could see shots of the back balcony being dismantled. They (Phil and Mel) did a daily competition beneath it. The lights had been removed from the balcony so it was darker, and you could see wires hanging down.