Dog urinating in living room

[Shinesun9]

Have a small breed dog, we've had him from a pup and for 2 1/2 years.
Generally very good, have youngish dc and he's very good around them. Very affectionate and loves attention.
Take him out every morning on the school run where he goes to toilet and out for 5 in the evening, but keep a mat near our front door as we live in an apartment and not always able to leave at the drop of a hat with toddler.
I keep mine and my older dcs bedroom doors shut during the day (mainly to keep toddler out) so he doesn't go in there but if he's in the living toom will place mark - but only when I'm not in there, and it seems he does it within minutes of me leaving the room.
Now I know he will mark on anything like carrier bags/washing baskets so don't leave them on the ground but the last few days he's marked against my sofa and against a few of toddlers toys, which obviously can't keep away.

Any suggestions?

Sorry for the long post, didn't want to drip feed

If this is a new behaviour I'd be getting him checked out at the vet to make sure there's no infection that's making him wee.

When you say, you have a mat by the door, do you mean a mat for him to wee on when you can't get him outside? If that's the case, he won't understand the difference between inside and outside when it comes to toileting so will go anywhere inside the house, in the same way that he would outside. Get rid of the mat, stop allowing him to wee in the house and teach him that outside is the only place to go.

Unfortunately I think if you have a mat he can toilet on inside the house it confuses the matters as I am not sure that he will know that inside BUT only on the mat is ok. Also because he has now been going frequently inside he is going to keep going unless you 100% get rid of the smell AND train him to do it outside.

Thanks both, will get him checked out as this is quite a recent occurrence, usually he would go in the morning and evening outside and then occasionally (but not everyday) on the mat but always just on the mat never anywhere else around the house unless someone leaves a bag lying about as he loves to urinate on them.

Unless he has a UTI he's learnt it is ok to toilet inside the house I am afraid.
You need to take him out far more often.

"we live in an apartment and not always able to leave at the drop of a hat with toddler."

Why would you need to?

Adult housetrained dogs don't need taking out at the drop of a hat. They're capable of having a routine and waiting for a bit... just not all day.

Yes, you probably do need to take him out more often. Once in the morning and again in the evening isn't leaving him much wiggle room.

What about before bed? Going from 5 at night until the school run is an awfully long time.

If he's urinating when you aren't there it may be he's waiting for you to leave so he can go. If he's been told off for weeing in the house then he won't do it in front of you.