The new brick looks ok. So you have a dark roof and white windows in the extension. Is this the same on the original building? If so I’d paint the brick of the original building the dark roof colour for a modern vibe. Add a lush garden landscaping and a decked entry for real oomph. This pic for colour inspiration.

Thanks for quick response! If we had chosen a nicer brick then then they would have been a great idea. Unfortunately, in person, the brick extension doesn't look very good.

Sounds like you don’t like the new brick. So I’d paint the lot. You can get textured paint that give a rendered feel. You’ll still see a difference between old and new - but in reality it was never going to be a seamless extension so embrace the difference.

I second @bigreader 's design idea and also the philosophy of "embracing the difference". There is nothing wrong with showing a house's journey through time - if can be done well. Buildings that survive changes in needs, are ones that learn and gain more character as well as practicality. If you can live with one brick colour, keep it and paint the other (no point creating more work down the track in the form of painting more than you have to). Just a thought :)

Give the original home, white bricks, a good clean, especially at the join between old and new bricks.

paint the new bricks with a textured paint. Look at the Dulux textured paint range.

I would go with bigreader, old white bricks can get very shabby so painting them a dark colour would be a good start. I love the bricks in the extension so would work with keeping them you might need to repoint some of the concrete grout with more concrete. This is a very rough mock up

It looks to me that , looking from the street , the one join on the right side can't really be seen , the other one is a right angle , so neither can be seem clearly from the street ? You don't like the redder bricks , the barge boards are bluish coloured all the way around , the tiles are similar ?

The white bricks actually look similar to painted ones , and you were presumably going to do a white bagging ?

I'd be tempted to paint the red bricks in the textured paint as the above writers have said , as close to the front as you can get ( after waterblasting the front ) to the white/off-white . Then , were the join is , the bricks don't even match up , so I'd do a 150mm x 150mm 'post' up that wall , stained charcoal , and do a fence with a gate across to your boundary , also stained charcoal , just to 'hide that join .

Thanks for the suggestions, I think the textured paint sounds like the way. If I were to leave the existing house colour as is, what colour should the extension be?

I'd say stick with the off-white . Even if people realise it is different styles , it looks designed like that , and to me , the fact that the right side wall is 'straight' means it is logical to carry the same theme through .

Bigreaders picture , and to a certain degree siriuskeys , show different colours but that works best with defined corners , shapes , heights and the like .

I think you need to clean the existing bricks and see what colour they come up as. You’ve already chosen the window colour and the guttering/roofing plus the existing house gives you three colours to work with. Anymore and it will start to look bitsy. So either the roofing colour which would look great with green landscaping or match to the cleaned up existing house colour.

The red bricks are face bricks used if you are going to render or clad.

they are not for leaving raw. In my opinion, they need to be covered. A dark colour would look good, but what colour are your new window frames? They are covered at the moment, and you haven't mentioned what colour they are.

Example of colour choice

Given the diff bricks I would go two colours, old and new as per dreamer. I like bagging that shows the crevice lines rather than trying to make it flat.

yes, sorry I wrote face brick but meant common brick, they are roigh faced to be covered as dreamer mentioned.
I think we will play with a colour scheme and have just the extension bag rendered and painted. Thanks for the help!

The window frames are white, it's just an opaque sticker with words over the top to protect them

Because your bricks are so different, I would go full render as bagging will still show the ridges in the new red bricks. We have 2 houses opposite use with the white bircks and when they get wet they always look patchy and dirty, one house is just having a new metal roof to replace the old tiles and then it will be rendered. I would bite the bullet and render the whole house white.

I have made a couple of options for the exterior. Firstly, either dark or light colour for the street facing wall, and then either render or cladding for a dark coloured wall at the side which will break up the transition from old to new. The dark colour is Monument which is the colour of the gutters and garage door.

Pic 3 and pic 4 look the same , but I think you have gone the wrong way .

From the street , you will see cream , then it changes to brown for 4 metres , then you possibly won't see the rear , or if you do , it's back to cream . If the bit you wanted to do in brown 'jutted' out , I'd say go for it , but on a straight wall , I'd try and match things reasonably closely , BUT have a fence/gate across to distract the eyes -- sort of an each way bet .

Good work on the mock ups. I prefer the dark. It looks quite good. But paint the infill above the front window the same colour as the wall whichever way you go - you don’t need to advertise that you economised on full brick.

Or I suppose we could go dark for the entire extension?

All dark all the way from me. Now you get to plan the garden.

With a coloured statement front door in your fav colour.

monument paint for the whole thing. can't go wrong

Fabulous

Looking good.

Yep , looks good ! The older white bricks now look even less cared for though , so a blast or a chemical clean .

Also , the window with the pointy facade above it , looks a bit average as it is IMO . You have the contour and point of difference there , but painting it the same just means it blends in . The main render colour is charcoal with a blue tone -- I'd do the pointy bit in a lighter silvery blue just to add interest , without being too dramatic or different .

It will look great once those bricks are cleaned as Pottsy said .

Plumbers could have done a better job on that down pipe to avoid the window. Render looks fab!

The downpipe was temporary until they put in the stormwater tank. That and the front porch are now also done.

I'm in NZ , so obviously 'looks good' means something different in Aus . . . . .

I had this idea you would try and tie the old and the new in so it looked matched or at least similar . The new is rendered in a blueish shade, the old is brick in a cream shade . The roof lines don't match . The old has brown tile that curves over the trim . The new appears to have a blue roof that curves over the trim .

Even Stevie Wonder could spot the differences .