Please ignore if this isn't of use. Sorry it's long.
I have hoarding disorder and very likely inattentive ADHD. 2nd generation hoarder who grew up in a squalor hoard and very aware of its effects from both ends.
Your thread has flagged on my notifications because a poster has linked it to another I’ve talked about hoarding on in detail, also in ‘relationships.’ You might find some of the detail on it useful.
I’m so sorry you are living in this situation. Hoarding’s a miserable pernicious and very serious MH disorder, and an industry has grown up around it that makes a lot of money keeping hoarders needing services, possibly because there's no actual cure, just self- awareness, followed by self-management.
Even as a self-aware hoarder who desperately wants to change, it is extremely difficult to get actual help. But nothing can change until the individual with the disorder wants to change.
You've three deeply connected problems. Separating them out may help you.
His hoarding issues
His beginning but not finishing projects
Your mutual ages
It is the middle one that is breaking your marriage and destroying your happiness most and fastest. Your ages and the way your husband responds to issues, mean your chances of solving things through self help are tbh very low.
The waiting list for diagnosis for ADHD investigation is now years, and the chances of getting medication for it (legally) without diagnosis is slim. Happyinarcon who raised it, is correct about trauma usually being involved in flight, freeze, behaviors, and it being a bugger to unravel.
Throwing things out surreptitiously or forcibly as someone else suggested, exacerbates the behavior in the person with the disorder, it makes others feel better for the short term but longer-term backfires on everyone. The idea the hoarder will never know is a fallacy. They may not initially realize, but once they do or suspect it, it causes massive insecurity deepening the impulsive behavior. In some individuals it can result in violence.
Fire brigade fitting alarms if you don’t already have them, may help him see his behaviors in a different light, but this is generally an early baby step rather than a big wake up, and may not be helpful if most of his hoard apart from the DIY tools is confined to outside the house.
IME SW ‘monitoring’ is only helpful if you have a very insightful SW and an LA interested in helping residents overcome issues, and not just wanting to charge for ‘services,’ which if he then doesn’t pay for can result on a lien on the house.
There really aren’t simple easy fixes for this situation even when the person really wants them and less so when the person is still in the denial phase.
Given your ages, his lack and your desire for a decent home where you can have your grandchild, sadly, separate accommodation is likely to be your best bet.
If that’s to bad an option for you, then your next best bet is to learn about hoarding and start working on the situation as a partner who wants to help him solve his problems, rather than a partner whose had enough. You shouldn’t have to obviously, but second has already been shown not to work with him, the first can, but it’s very time and energy consuming. (For many, love and understanding that we feel we don’t deserve can allow us address issues and get things moving. Criticism and blame that we feel we do deserve, puts us in defense mode and shuts us down.)
The 'I’m going to start a project, and run out of interest in it’ is the deal breaker here, because it sounds like he is in denial of the practical misery he is actively, (ripping things out) rather than passively, (keeping everything) creating.
It is giving him a sense of being in control of things, moving forward, still being ‘vigorous’ and being ‘his own man’, while actually drawing attention to how far out of control, not vigorous or ‘his own man’ he actually is.
Part of hoarding is that it's generally an exterior manifestation of deeply suppressed internal pain and problems that the person either wont or can’t acknowledge. It's maladaptive behavior, but we don't know that for decades.
The external behavior forces unwanted attention onto the fact the person is hiding or has buried a mess inside. The hoard and extreme attachment to items is a maladaptive behavior symptom, that forces the fact somethings wrong inside, out into the light and doesn’t help them or those around them unless it's recognized, and generally by then, so much damage has been done to everyone around them.