Given that hot air raises, have you considered a Passive Stack Ventilation system. Basically:
- A tall pipe coming out of the top of your loft so the hot air can raise
- You must not have bends in the pipe or it does not work as well
- The topping on the pipe must not add much to the flow resistance
- The sizing of the pipe is important (sorry can’t help on this)
- Too wide you don’t get fast enough upwards air movement.
- Not wide enough, you get to much air resistance
- The pipe must come out of the top of the loft and be high enough above the roof
- Soffit venting of some type so the colder air can get in at the bottom
The system will only tent to pull air though the loft when the outside air is colder than the air in the loft (just what you need).
Given the correct conditions and design, a Passive Stack Ventilation system will work forever with no running cost or maintenance. Get anything wrong and it will not work at all.
Also check that your ceilings are well sealed, otherwise all the expensive cold air from your AC will just go up into the loft and be vented out.
In addition to the basics, seen in this answer: What are some of the best books/resources on home inspection for first time home buyers?, the fact that someone's been messing around with the innards of the house means you should pay extra attention to the areas you know they've worked on, and whatever's around it.
You mentioned they replaced the roof. Get up into the attic and look at the job from underneath. Do you see any signs of recent leakage (wet wood, drips, ice, stains)? Water damage that looks older MAY be OK, but if the wood appears rotten or mouldy, they didn't go deep enough in their demo when re-roofing.
Windows can be problematic. If the flipper enlarged the window frames, and did so improperly, this is a whole world of problems for you. They could have taken out the header, or installed a new one improperly, putting the weight of your house on the window frame itself instead of letting studs and plates do it. They could have weakened the jack or (God forbid) king studs which transfer the weight from the header and top plate down to the foundation, again around the window frame without putting load on it. If they cut out brick, they may not have installed a proper lintil in the brickwork. All of these can make the house settle down onto your window frame, making them hard to open/close and in the extreme collapsing the frame, breaking the window and making the structure above extremely unstable.
Doors are similar; you have to have a proper header, jack stud, and king studs supporting the frame, otherwise the structure of the house will bear down and collapse the frame onto your door, and you'll never get it back out. If the flipper changed out exterior doors, you may have some security issues related to the screws in the hingeplates and the strikeplate; if those don't go into the studs on either side of the frame, the door can be kicked open pretty easily.
Plumbing is also difficult for a novice to get right. Worse than electrical IMO, but I'm more comfortable with wiring work than plumbing personally. Unlike electrical wiring, water is dependent on gravity to work properly. Slope of the pipes, proper P-traps, proper installation of T-junctions and other joints to allow for the free flow of water (and making sure the joints don't leak), all of these are things the average home flipper looking to add a sink to the master bath and rearrange the shower and tub may not be taking into account.
To check for plumbing problems, first smell all the drains. If you smell sewer gas or general decomposition, odds are someone didn't put in a trap. Or, the trap has gone dry, in which case if you run some water down the drain and then come back and smell it later, the smell should be gone.
Then, for sinks, open the tap full blast with the drain open. The water should drain quickly and should not back up. If it drains slowly or backs up, you might have an improper slope on the drain line, or the sink might be too far from a vent stack. For tubs/showers, use the faucet to fill a bucket, then pour it down the drain. Again, the tub should drain quickly (though this is a lot more water than you were running down the sink so it will take a few seconds to drain fully). Check for leaks on all pipes you can see; evidence of drips, mould, etc etc.
Best Answer
Those look like temporary supports judging from the lack of fasteners, and if so, there's nothing wrong with supporting something temporarily in whatever way works. I just assume because I don't think most tradesmen would leave an unfastened but somehow necessary 2x4 passing through a living space at an odd angle. If you look on Youtube there are videos of people doing solo framing erection, using simple ropes, levers, wedges and 2x4 temporary props to hold things in place while they're tacked together. Sometimes they are forgotten and left in place, but this is unlikely to cause a problem because of the typical limited weight.
If so, they have really nothing to do with the long term reliability or stability of the framing. Either way, you may need an engineer if you want to speculate on the long term reliability, stability or load bearing capacity of the actual permanent roof members. Presumably you have already had this done, so you could compare the plan to what was actually built.
If this is intended to be permanent and critical support and has more fasteners than I see, it does look a bit iffy to me, and the solution is the same. See what the engineering diagrams indicate and if it differs, have the tradesman in question demonstrate his calculations and that he had a right to make them (I'm an electrician, and electricians are given authority to calculate certain things, and with other things absolutely must follow specifications provided by other professionals, so I would imagine framers are trained and have at least some ability to calculate and rework supports.